EXHIBIT 10(bb)

                         AGREEMENT OF PURCHASE AND SALE


                                     BETWEEN


                             WATERFORD PARTNERSHIP,
                    A CONNECTICUT GENERAL PARTNERSHIP, SELLER


                                       AND


                              CASE VENTURES, INC.,
                       AN OKLAHOMA CORPORATION, PURCHASER










                                TABLE OF CONTENTS

                                                                                                               Page
                                                                                                            

Article I.        Property........................................................................................1

Article II.       Purchase Price and Deposits ....................................................................4

Article III.      Failure to Close................................................................................6
                  3.1      Purchaser's Default....................................................................6
                  3.2      Seller's Default.......................................................................7
                  3.3      Termination of Agreement in Accordance with its Terms..................................7

Article IV.       Closing and Transfer of Title...................................................................8
                  4.1      Closing................................................................................8
                  4.2      Closing Procedure......................................................................8
                  4.3      Purchaser's Performance...............................................................11
                  4.4      Bond-Related Documentation; Special Condition to Purchaser's
                           Obligations; Release of Seller from Bond Obligations..................................11
                                    4.4.1   Bond-Related Documentation...........................................11
                                    4.4.2   Special Condition to Purchaser's Obligations.........................13
                                    4.4.3   Release of Seller from Bond Obligations and from Existing
                                            Credit Enhancement Liability.........................................15
                                    4.4.4   Fees and Costs.......................................................16
                                    4.4.5   No Covenants.........................................................16
                  4.5      Evidence of Authority; Miscellaneous..................................................17
                  4.6      Assignment and Assumption of Partnership Interests in Seller..........................17

Article V.        Prorations of Rents, Taxes, Etc................................................................18

Article VI.       Purchaser Inspections and Contingencies........................................................20
                  6.1      Document Inspection...................................................................20
                  6.2      Physical Inspection...................................................................21
                  6.3      Feasibility Period ...................................................................21
                  6.4      Survey Contingency....................................................................22
                  6.5      Title Contingency.....................................................................22

Article VII       Loss due to Casualty or Condemnation...........................................................24
                  7.1      Loss due to Condemnation..............................................................24
                  7.2      Loss due to Casualty..................................................................25

Article VIII.     Seller's Operation and Maintenance of the Property Prior to Closing............................26

Article IX.       Broker.........................................................................................27

Article X.        Representations and Warranties.................................................................27
                  10.1     Limitations on Representations and Warranties.........................................27
                  10.2     Representations and Warranties of Seller..............................................28







                          TABLE OF CONTENTS (CONTINUED)
                                                                                                               Page

         10.3     Seller's Knowledge.............................................................................32
                  10.4     Representations and Warranties of Purchaser...........................................32
                  10.5     Survival..............................................................................33

Article XI.       Liability of Seller............................................................................34

Article XII.      Assignment.....................................................................................35

Article XIII.     Notices........................................................................................36

Article XIV.      Expenses.......................................................................................37

Article XV.       Miscellaneous..................................................................................38
                  15.1     Successors and Assigns................................................................38
                  15.2     Gender................................................................................38
                  15.3     Captions..............................................................................38
                  15.4     Construction..........................................................................38
                  15.5     Entire Agreement......................................................................39
                  15.6     Recording.............................................................................39
                  15.7     No Continuance........................................................................39
                  15.8     Time of Essence.......................................................................39
                  15.9     Counterparts..........................................................................39
                  15.10    Governing Law.........................................................................40
                  15.11    Acceptance of Offer...................................................................40
                  15.12    Confidentiality.......................................................................40
                  15.13    Surviving Covenants...................................................................40
                  15.14    Real Estate Reporting Person..........................................................41
                  15.15    Independent Contract Consideration....................................................41
                  15.16    Exclusive Period......................................................................41
                  15.17    Approval..............................................................................41
                  15.18    Business Day(s).......................................................................42

EXHIBIT A         DESCRIPTION OF LAND
EXHIBIT B         RENT ROLL
EXHIBIT C         CONSENT AND RELEASE AGREEMENT
EXHIBIT D         SPECIAL WARRANTY DEED
EXHIBIT E         BILL OF SALE AND GENERAL ASSIGNMENT
EXHIBIT F         ASSIGNMENT AND ASSUMPTION OF LEASES AND SECURITY
                  DEPOSITS
EXHIBIT G         INDEMNIFICATION AGREEMENT
EXHIBIT H         FORM OF SELLER'S AFFIDAVIT OF NON-FOREIGN STATUS
EXHIBIT I         DUE DILIGENCE MATERIALS
EXHIBIT J         PENDING LITIGATION
EXHIBIT K         ASSIGNMENT OF AND AMENDMENT TO AGREEMENT OF PURCHASE
                  AND SALE
EXHIBIT L         LIST OF PERSONAL PROPERTY
EXHIBIT M         LIST OF SERVICE CONTRACTS
EXHIBIT N         BOND DOCUMENTS
EXHIBIT O         ASSIGNMENT AND ASSUMPTION OF PARTNERSHIP INTERESTS




                                                                               
                         AGREEMENT OF PURCHASE AND SALE

                  THIS AGREEMENT OF PURCHASE AND SALE (THIS "AGREEMENT") is made
by  and  between  WATERFORD  PARTNERSHIP,   a  Connecticut  general  partnership
("SELLER"),  and CASE VENTURES, INC., an Oklahoma corporation,  ("PURCHASER") or
its designee, or assignee as of the "EFFECTIVE DATE" (as defined below).

                                    Article I
                                    Property

                  Seller hereby agrees to sell,  and Purchaser  hereby agrees to
buy, all of the following  property:  (a) a parcel of real property,  located in
the City of Tulsa,  Oklahoma,  more particularly described on Exhibit A attached
to this Agreement and made a part hereof,  together with  Assignor's  assignable
right,  title,  and interest  in, to and under (i) all and  singular  easements,
covenants,   agreements,  rights,  privileges,   tenements,   hereditaments  and
appurtenances  thereunto now or hereafter belonging or appertaining  thereto and
(ii) any and all oil, gas and mineral rights relating to the real estate,  water
and water rights,  and water stock, and all right,  title and interest of Seller
(whether now or  hereafter  existing) in and to any land lying in the bed of any
street,  alley,  road or avenue (whether open,  closed or proposed)  within,  in
front of, behind or otherwise adjoining the real estate or any of it and if, and
only to the extent expressly  provided  elsewhere in this Agreement,  all right,
title and interest of Seller  (whether now or hereafter  existing) in and to any
award made or to be made as a result or in lieu of condemnation, and if and only
to the extent



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expressly provided  elsewhere in this Agreement,  in and to any award for damage
to the  Property or any part thereof by reason of casualty  (collectively,  "THE
LAND"); (b) the buildings, structures,  fixtures, facilities,  installations and
other  improvements  now or  hereafter  located in, on, over and under the Land,
being a 344-unit  apartment  complex  containing  an aggregate of  approximately
230,676  square  feet  of net  rentable  area,  generally  known  as  "Waterford
Apartments",   including,   without  limitation,   any  and  all  plumbing,  air
conditioning,  heating,  ventilating,  mechanical,  electrical and other utility
systems, parking lots and facilities, landscaping, roadways, sidewalks, swimming
pools and  other  recreational  facilities,  security  devices,  signs and light
fixtures (collectively, the "IMPROVEMENTS");  (c) the landlord's interests under
all tenant leases relating to the Improvements,  being the leases referred to on
the Rent Roll  attached  hereto as  Exhibit B (as such  leases  may expire or be
terminated in the ordinary course of business),  together with any tenant leases
hereafter   entered  into  pursuant  to  the   provisions   of  this   Agreement
(collectively,  the  "LEASES")  (the  Land,  Improvements,  and the  Leases  are
referred to herein,  collectively,  as the "REAL PROPERTY"); (d) all of Seller's
assignable  right,  title and interest,  all furniture,  furnishings,  fixtures,
fittings, appliances,  apparatus, equipment, machinery, maintenance vehicles and
equipment,  tools, parts, recreational equipment,  carpeting, window treatments,
stationery and other office supplies, and other personal property (the "TANGIBLE
PERSONAL PROPERTY"), including, without limitation, the items shown on Exhibit L
attached hereto and made a part hereof; (e) all Seller's assignable right, title
and  interest  in  all  existing  surveys,  blue  prints,  drawings,  plans  and
specifications (including, without limitation,  structural, HVAC, mechanical and
plumbing plans and  specifications)  and other documentation for or with respect
to the Real Property or the Tangible Personal Property, or any part thereof; all
use, occupancy, building and



AFL\WATERFRD\P&SIGMOID.005  (3-5-99)                                     Page 2






operating  permits,  licenses and approvals relating to the Real Property or the
Tangible Personal Property;  all marketing artwork,  construction  drawings, all
guaranties,  warranties,  booklets,  manuals  and  promotional  and  advertising
materials  exclusively  concerning  the Real  Property or the Tangible  Personal
Property,  or any part  thereof;  and such other  existing  books,  records  and
documents (including, without limitation, those relating to ad valorem taxes and
leases) used exclusively in connection with and integral to the operation of the
Real Property or the Tangible Personal  Property,  or any part thereof,  and all
other intangible personal property,  together with any associated good will, now
or hereafter  owned by Seller or in which Seller  otherwise  has an interest and
used  exclusively  in  connection  with or  arising  from  the  business  now or
hereafter conducted on or from the Real Property or any part thereof, including,
without limitation,  claims,  choses in action, lease and other contract rights,
names,  and,  if  available,  telephone  exchange  numbers  (collectively,   the
"INTANGIBLE   PERSONAL  PROPERTY")  (the  Tangible  Personal  Property  and  the
Intangible  Personal  Property shall  hereinafter be referred to collectively as
the "PERSONAL PROPERTY");  (f) all Seller's assignable right, title and interest
in and to all purchase,  service and maintenance  agreements,  cable  television
agreements,  laundry facility leases, equipment leases and any other agreements,
contracts,  licenses and permits exclusively affecting or exclusively pertaining
in any way to the Real Property or the Personal  Property,  or any part thereof,
including,  without  limitation,  the property  management  agreement  and those
listed on  Exhibit M  attached  hereto  and made a part  hereof,  (the  "SERVICE
CONTRACTS")  (collectively,  the Real  Property,  the Personal  Property and the
Service Contracts are sometimes  referred to herein as the "PROPERTY").  As used
herein, unless otherwise expressly stated, the term "assignable" shall mean



AFL\WATERFRD\P&SIGMOID.005  (3-5-99)                                     Page 3






assignable  without any additional cost to Seller on account of such assignment,
other than de minimis and incidental transactional costs.

                                   Article II
                           Purchase Price and Deposits

                  The purchase  price which the Purchaser  agrees to pay and the
Seller  agrees to accept for the Property  shall be the sum of Fourteen  Million
Six Hundred Seventy-Five  Thousand Dollars ($14,675,000) (the "PURCHASE PRICE"),
subject to  adjustment  as provided in Article V hereof,  as to which  Purchaser
shall receive a credit  against the balance of such Purchase Price at Closing in
the amount equal to the unpaid principal balance (as of the Closing Date) of the
Bonds (as defined in Section 4.4.1 hereof).  The Purchase Price shall be payable
as follows:

                  (a) An  initial  earnest  money  deposit  (together  with  any
         interest  earned thereon,  the "INITIAL  DEPOSIT") in the amount of One
         Hundred  Thousand Dollars  ($100,000),  in cash, which has already been
         deposited with Frisco Title Insurance  Company (the "TITLE COMPANY") in
         Tulsa,  Oklahoma,  such amount to be held in escrow in accordance  with
         the  terms  of  this  Agreement  in an  interest-bearing  account  (the
         "INITIAL ACCOUNT");

                  (b)  An  additional   earnest  money  deposit  (together  with
         interest  thereon,  the  "ADDITIONAL  DEPOSIT")  in the  amount  of Two
         Hundred  Thousand  Dollars  ($200,000)  to be deposited  with the Title
         Company at the time Purchaser delivers this Agreement to the



AFL\WATERFRD\P&SIGMOID.005  (3-5-99)                                     Page 4






         Title Company in accordance with the last paragraph of this Article II,
         such amount to be held in escrow in  accordance  with the terms of this
         Agreement  in an  interest-bearing  account  in the  State of  Oklahoma
         according to this Agreement (the "ESCROW  ACCOUNT"),  at which time the
         Title  Company  shall  transfer  the Initial  Deposit  from the Initial
         Account to the Escrow  Account to be held pursuant to the terms of this
         Agreement  (the  Initial  Deposit and,  upon deposit of the  Additional
         Deposit as provided  above,  the  Additional  Deposit are  collectively
         referred to as the "DEPOSIT");

                  (c) The  execution  and  delivery by Purchaser at Closing of a
         Release  and  Indemnification   Agreement  substantially  in  the  form
         attached  hereto  as  Exhibit  C  (the  "RELEASE  AGREEMENT"),  whereby
         Purchaser  shall  assume  all of  Seller's  obligations  under the Bond
         Documents (as defined in Section 4.4.1 hereof) occurring from and after
         the Closing, all in accordance with the terms of the Release Agreement;
         and

                  (d) The balance of the Purchase  Price (less the amount of the
         Deposit)  shall be paid at time of Closing by  Federal  wire  transfer,
         with the  transfer  of funds to  Seller  to be  completed  and the sale
         proceeds  received by Seller no later than 4:00 p.m.  E.S.T. on the day
         of the Closing.

                  Purchaser  shall  provide  the  Title  Company  with  its  tax
identification number, and all interest shall be for Purchaser's account for tax
purposes.




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                  In addition,  Purchaser shall deposit three (3) fully executed
original counterparts of this Agreement with the Title Company immediately after
both parties have executed it. The date of such deposit shall be acknowledged by
the  Title  Company  on all  such  counterparts,  and  such  date  shall  be the
"EFFECTIVE  DATE" of this Agreement.  The Title Company shall retain one copy of
this Agreement and deliver one (1) copy hereof to each of Purchaser and Seller.

                                   Article III
                                Failure to Close

         3.1  Purchaser's  Default.  If  Seller  has  complied  with  all of the
covenants  and  conditions  contained  herein and is ready,  willing and able to
convey the Property in accordance with this Agreement and Purchaser  defaults in
its obligations under this Agreement,  including, without limitation, failing to
consummate this Agreement and take title,  then the parties hereto recognize and
agree that the  damages  that Seller will  sustain as a result  thereof  will be
substantial,  but  difficult if not  impossible  to  ascertain.  THEREFORE,  THE
PARTIES AGREE THAT, IN THE EVENT OF  PURCHASER'S  DEFAULT,  THE DEPOSIT SHALL BE
FORFEITED TO SELLER AS  LIQUIDATED  DAMAGES,  AND AS SELLER'S SOLE AND EXCLUSIVE
REMEDY AT LAW AND IN EQUITY,  AND BOTH PARTIES SHALL BE RELIEVED OF AND RELEASED
FROM ANY  FURTHER  LIABILITY  UNDER THIS  AGREEMENT,  EXCEPT  FOR THE  SURVIVING
COVENANTS (AS HEREINAFTER DEFINED).  SELLER AND PURCHASER AGREE THAT THE EARNEST
MONEY IS A FAIR AND REASONABLE AMOUNT TO BE RETAINED BY SELLER AS AGREED AND



AFL\WATERFRD\P&SIGMOID.005  (3-5-99)                                     Page 6






LIQUIDATED DAMAGES IN LIGHT OF SELLER'S REMOVAL OF THE PROPERTY
FROM THE MARKET AND THE COSTS INCURRED BY SELLER AND SHALL NOT
CONSTITUTE A PENALTY OR FORFEITURE.

         Initials:Seller_____________                Purchaser____________

         3.2 Seller's Default. In the event that Purchaser has complied with all
of the covenants and conditions  contained herein and is ready, willing and able
to take title to the  Property in  accordance  with this  Agreement,  and Seller
defaults in its obligations under this Agreement, including, without limitation,
failing to consummate  this  Agreement and convey title as set forth herein,  or
breaches any representations or warranties set forth herein, then Purchaser may,
as its sole remedy,  either (i) terminate this  Agreement and pursue  recovering
all actual  expenses  incurred by Purchaser in connection  with this  Agreement,
including,  without limitation, its reasonable attorney's fees, or (ii) bring an
action for specific performance of this Agreement.

         3.3 Termination of Agreement in Accordance with its Terms. In the event
that this  Agreement is terminated in  accordance  with its terms  pursuant to a
right to do so as expressly provided in this Agreement (other than a termination
by Seller  pursuant  to Section 3.1  above),  the  Deposit  shall be returned to
Purchaser  and no other  party  shall  have any  further  rights or  obligations
hereunder, except for the Surviving Covenants.




                   AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 7






                                   Article IV
                          Closing and Transfer of Title

         4.1 Closing. The parties hereto agree to conduct a closing of this sale
(the "CLOSING") on or before April 9, 1999 [30 days after end of the Feasibility
Period],  or on or before  April 13, 1999 [15 days after the end of the Extended
Bond Financing  Approval  Period],  if applicable,  (such actual date of Closing
shall be referred to herein as the "CLOSING  DATE"),  in the local office of the
Title  Company,  or at such  other  place as may be agreed  upon by the  parties
hereto. This Agreement shall automatically  terminate,  subject to any Surviving
Covenants,  if transfer of title is not  completed  by the date  provided  above
(unless (i) such  failure to close is due solely to Seller's  default,  (ii) the
date for Closing is extended  pursuant to any express provision hereof, or (iii)
the date for Closing is extended by agreement of the  parties,  which  agreement
shall be confirmed in writing).

         4.2 Closing  Procedure.  At the Closing,  Seller shall  execute  and/or
deliver  or cause to be  delivered  to  Purchaser,  or, in the case of the items
covered by clauses (e), (f), and (j) below,  to be available to Purchaser at the
Property (a) a Special  Warranty Deed, in the form attached hereto as Exhibit D,
proper for  recording,  conveying  Seller's  interest  in the Real  Property  to
Purchaser,  subject,  however,  to (i)  exceptions  as  reported  in  the  Title
Commitment (defined in Section 6.5 below, (ii) any and all easements,  rights of
way, encumbrances,  liens, covenants,  restrictions, or other matters of record,
(iii) any and all  matters  shown on the  Survey  (as  defined  in  Section  6.4
hereof),  (iii)  taxes not yet due and  payable,  (iv) the rights of lessees and
licensees of space in the



                   AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 8






Improvements  at the time of  Closing  (to the  extent  shown  on the Rent  Roll
delivered at Closing or as otherwise provided under this Agreement), and (v) any
encumbrances created or permitted by the terms of this Agreement, except in each
case for title or survey matters which Purchaser  objects to in writing prior to
the expiration of the Feasibility  Period and which Seller  expressly  agrees in
writing to cure prior to Closing (collectively, the "PERMITTED EXCEPTIONS"); (b)
a bill of sale (the  "BILL OF SALE") in the form  attached  hereto as Exhibit E,
dated as of the date of Closing  conveying  to  Purchaser  any and all  Personal
Property and the Service Contracts; (c) an assignment of Leases (the "Assignment
of Leases and  Security  Deposits")  in the form  attached  hereto as Exhibit F,
dated the date of Closing,  assigning  all of the  landlord's  right,  title and
interest in and to all of the Leases;  (d) Tenant  Notification  Agreements (the
"TENANT  NOTICES"),  dated the date of the  Closing,  executed  by  Seller,  and
complying with  applicable  statutes in order to relieve Seller of liability for
tenant security deposits (provided the security deposits are paid to Purchaser),
notifying the tenants that the Property has been sold to Purchaser and directing
the tenants to pay rentals to Purchaser (or Purchaser's  designated  agent); (e)
the originals of all Leases,  (f) to the extent in the  possession or control of
Seller  or  Seller's  property  management  company,   (i)  as-built  plans  and
specifications,  surveys,  site plans,  engineering  plans and studies,  utility
plans,  development  plans and  marketing  artwork,  (ii) the  originals  of all
guaranties and warranties  relating to the Property,  (iii) the originals of all
governmental licenses and permits relating to the Property,  including,  without
limitation,  a currently effective certificate of occupancy,  (iv) the originals
of all books and records of the Property,  (v) all Service  Contracts,  and (vi)
all maintenance records; (g) an indemnification  agreement (the "INDEMNIFICATION
AGREEMENT") in the form attached as Exhibit G, dated the date of Closing; (h) an
affidavit that



                   AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 9






Seller is not a  "foreign  person"  in the form  attached  as  Exhibit  H; (i) a
duplicate key for all locks in the Improvements;  (j) the Release Agreement; and
(k) a termite  inspection report reasonably  satisfactory to Purchaser dated not
more than sixty (60) days prior to the Closing Date.

         In addition, if required by the Title Company,  Seller shall deliver to
the Title  Company a reasonable  Seller's  affidavit,  negotiated  in good faith
between  Seller and the Title  Company,  as to matters  concerning  title to the
Property  which can only be  reasonably  ascertained  by the Title  Company from
Seller  and  which  are  actually  known  to  Seller  "to the  best of  Seller's
knowledge", as that term is described in Section 10.3 hereof.

         Purchaser  acknowledges  and agrees that,  except for objections  which
Seller expressly agrees to cure in accordance with Section 6.4 or in Section 6.5
hereof, Seller is under no obligation under the terms of this Agreement to clear
from  title  any  easements,  rights  of way,  encumbrances,  liens,  covenants,
restrictions, or any other matters of record or to cure any Survey objections of
Purchaser,  or to  create  any  encumbrances  on,  or for the  benefit  of,  the
Property.  If Seller does not deliver  title at Closing  pursuant to the deed in
form  provided in clause  4.2(a)  above and such  failure is not a result of (i)
Seller's  acquiescence  in the placement of or failure to remove a monetary lien
(other than those  pertaining to the Bond  Financing or those caused by the acts
of Purchaser or its agents),  or (ii) Seller's  failure to pay real estate taxes
due and  payable,  such failure  shall not  constitute a breach of or default by
Seller  hereunder,  and  notwithstanding  any other provision of this Agreement,
Purchaser's  sole and exclusive  remedy shall be (i) to terminate this Agreement
and receive a prompt return of the Deposit, in which case neither party



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 10






shall have any further  obligations  pursuant to this  Agreement  except for the
Surviving Covenants,  or (ii) to accept conveyance by Seller of such title as it
delivers without reduction of the Purchase Price.

         4.3 Purchaser's Performance.  At the Closing,  Purchaser will cause the
Purchase Price, plus or minus  prorations,  less the unpaid principal balance of
the  Bonds,   to  be  delivered   to  Seller,   will  execute  and  deliver  the
Indemnification  Agreement,  the  Assignment  of Leases,  the Bill of Sale,  the
Release  Agreement,  and any other  documentation  as is  required  pursuant  to
Section 4.4 hereof to evidence Purchaser's  assumption of all the obligations of
the Seller under the Bond Documents (as defined in Section 4.4.1 hereof).

         4.4      Bond-Related Documentation; Special Condition to Purchaser's 
Obligations; Release of Seller from Bond Obligations.

                  4.4.1 Bond-Related  Documentation.  Acquisition,  construction
         and  development  of the Project was  financed  initially  by a loan to
         Seller's predecessor-in-interest (the "ORIGINAL BOND FINANCING") of the
         proceeds   received  from  the  sale  of  those  certain  Tulsa  County
         Multi-Family  Housing Revenue Bonds (Credit Enhanced Projects),  Series
         1985A in the original  principal  amount of $12,775,000  (the "ORIGINAL
         BONDS")  issued  by  the  Tulsa  County  Home  Finance  Authority  (the
         "ISSUER").  The obligations  represented by the Issuer's Original Bonds
         were refunded by the Multi-Family Housing Revenue Bonds, Taxable Series
         1993A  (Waterford   Project)  in  the  original   principal  amount  of
         $11,355,000



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 11






         (the "Tax Exempt Bonds") and the Issuer's  Multi-Family Housing Revenue
         Bonds,  Taxable  Series  1993B  (Waterford  Project)  in  the  original
         principal  amount of $400,000  (the  "Taxable  Bonds")  (the Tax Exempt
         Bonds  and  the  Taxable  Bonds  are  hereinafter  referred  to as  the
         "Bonds"). The current refunded bond financing (the "Bond Financing") is
         evidenced by (i) a Promissory  Note (Series 1993A Bonds) dated December
         1, 1993 in the original  principal amount of $11,355,000 from Seller to
         Issuer,  and (ii) a Promissory Note (Series 1993B Bonds) dated December
         1, 1993 in the  original  principal  amount of $400,000  from Seller to
         Issuer which was repaid in full on December 1, 1998, (collectively, the
         "Notes"),  and (iii) a Loan  Agreement  dated as of December 1, 1993 by
         and between Seller and Issuer (the "LOAN  AGREEMENT").  Issuer and Bank
         of Oklahoma,  National Association, as trustee (the "TRUSTEE") executed
         that  certain  Trust  Indenture  dated  as of  December  1,  1993  (the
         "INDENTURE")  for the purpose of  authorizing  and  securing the Bonds,
         prescribing the terms thereof and the conditions,  terms,  trusts,  and
         provisions upon which the Bonds were delivered and the proceeds thereof
         expended and held.  The Loan  Agreement,  the  Indenture,  that certain
         Escrow  Trust  Agreement  dated as of  December  1,  1993 by and  among
         Issuer,  Trustee and Seller,  the Tax Regulatory  Agreement dated as of
         December 1, 1993 by and among Issuer,  Trustee and Seller,  and any and
         all other  documents and agreements  evidencing,  securing or otherwise
         executed and delivered in connection  with the Bond Financing set forth
         on Exhibit N hereto are hereinafter  collectively referred to herein as
         the "BOND DOCUMENTS".




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 12






                  4.4.2 Special Condition to Purchaser's  Obligations.  It shall
         be a condition of Purchaser's obligations hereunder that it acquire the
         Property subject to the Bond Financing. Purchaser, at its sole cost and
         expense,  will use its good  faith  efforts  to  obtain  all  necessary
         consents, approvals and agreements required under the Bond Documents to
         its  purchase  of the  Property  or  its  purchase  of the  Partnership
         Interests (as hereinafter  defined)  subject to the Bond Financing,  to
         assume  the  Existing  Credit  Enhancement  Liability  (as  hereinafter
         defined)  or  obtain  and  provide   satisfactory   substitute   credit
         enhancement  for the  Bonds and to  release  Seller  from the  Existing
         Credit   Enhancement   Liability  in  accordance   with  the  Indenture
         ("ALTERNATE  SECURITY") and to otherwise satisfy the conditions of this
         Section  4.4.2 and Section  4.4.3.  As used  herein,  "Existing  Credit
         Enhancement Liability" shall mean (i) the Policy of Indemnity issued by
         AXA  Reinsurance UK Plc ("AXA") on December 1, 1993 to the Trustee,  as
         insured (the "Policy"),  (ii) the  Reimbursement  Agreement dated as of
         December 1, 1993 by and between Seller and AXA, and (iii) the Mortgage,
         Security Agreement,  Assignment of Rents and Leases, Fixture Filing and
         Financing  Statement  dated as of  December  1,  1993  from  Seller  as
         "Mortgagor" to Issuer and AXA, each as "Co-Mortgagee". Seller agrees to
         cooperate  with Purchaser to effect the obtaining of any such consents,
         provided  that Seller  shall not be  obligated to consent to (i) expend
         funds,  (ii) consent to,  agree to or cause any  amendment or agreement
         with respect to the Bonds or the Bond Financing which will be effective
         prior  to the  Closing  or upon a  failure  to  close  for  any  reason
         whatsoever,  (iii) make or give any  irrevocable  notices or  elections
         with respect to the Bonds,  the Bond  Documents  or the Bond  Financing
         which would be effective prior to the Closing which, in



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 13






         Seller's  sole  opinion,  in any case,  could result in any  additional
         liability,  monetary obligation,  or expense of Seller under the Bonds,
         whether or not the Closing occurs,  except as may be expressly provided
         herein.

                  Purchaser shall have until the end of the  Feasibility  Period
         (defined  in  Section  6.3 below) to obtain  all  required  assurances,
         consents,  approvals  and  agreements,  including  those of or with the
         Issuer,  the  trustee,  bond  counsel,  AXA,  or  the  provider  of any
         Alternate  Security  (which  shall be  unconditioned  except  for those
         conditions  which  can  only  be  satisfied  at and as of the  Closing)
         necessary for Purchaser to (a) acquire the Property or the  Partnership
         Interests subject to the Bond Financing, and (b) satisfy the conditions
         of Sections 4.4.2 and 4.4.3 of this Agreement (collectively,  the "BOND
         FINANCING APPROVALS");  provided,  however, that if Purchaser is unable
         to  obtain  the  Bond  Financing  Approvals  prior  to  the  end of the
         Feasibility  Period,  through  no fault  of  Purchaser,  Purchaser  may
         request  from Seller an extension of the time period to obtain the Bond
         Financing Approvals until March 29, 1999 (such period being hereinafter
         referred to as the "EXTENDED BOND FINANCING  APPROVAL  PERIOD"),  which
         request  must  be in  writing.  The  delivery  of the  request  for the
         Extended Bond Financing  Approval Period shall  constitute  Purchaser's
         agreement and acknowledgment of approval as to all other aspects of the
         Property and of the Bond  Financing and Bond  Documents  (with the sole
         exception  of being able to obtain the Bond  Financing  Approvals)  and
         shall constitute  Purchaser's  election not to terminate this Agreement
         for any  reason  other than its  failure  to obtain the Bond  Financing
         Approvals prior to the expiration of the Extended Bond



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 14






         Financing  Approval Period,  subject to Purchaser's rights to terminate
         the  Agreement  as set forth in Section  3.2,  Section 4.2, in the last
         sentence of this Section  4.4.2,  Article 7 and as otherwise  expressly
         set forth in this  Agreement.  In the event that,  after good faith and
         diligent  efforts  throughout  the  Extended  Bond  Financing  Approval
         Period,  Purchaser  is  still  unable  to  obtain  the  Bond  Financing
         Approvals,  either Purchaser or Seller may terminate this Agreement for
         such reason and have the Deposit  returned,  after which  neither party
         shall  have any  further  rights or  duties  hereunder  except  for the
         Surviving Covenants.

                  The parties agree that it shall be a condition of  Purchaser's
         obligations  hereunder  that,  on or prior to the  Closing  Date,  bond
         counsel  retained  by  Purchaser  shall have  issued its opinion to the
         effect  that  the  transfer  of  the  Property  to  Purchaser,  or  the
         assumption of the Partnership Interests by Purchaser, and the execution
         of the documents in connection therewith will not cause interest on the
         Bonds to be  includable in the gross income of the  recipients  thereof
         for federal income tax purposes.

                  4.4.3  Release  of  Seller  from  Bond  Obligations  and  from
         Existing Credit  Enhancement  Liability.  It is a condition to Seller's
         obligations  hereunder  that  Seller  and its  partners  be  fully  and
         unconditionally  released at Closing for all periods from and after the
         Closing Date from all  obligations  with regard to the Existing  Credit
         Enhancement  Liability with respect to the Bonds,  the Bond  Documents,
         the Issuer,  the Trustee,  and all other parties or circumstances  with
         respect to the Bond Financing, which releases shall be



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 15






         evidenced  by the  Release  Agreement  and a  corresponding  release of
         Seller and its partners from all Developer/Owner  obligations under the
         Bond Documents for all periods from and after the Closing Date.

                  4.4.4  Fees and  Costs.  Purchaser  hereby  agrees  to pay all
         costs,  expenses,  and fees due to any third party (other than Seller's
         outside   counsel  and  Seller's  bond  counsel)  in  connection   with
         Purchaser's  efforts to satisfy the conditions to Closing  contained in
         Sections  4.4.2 and 4.4.3 above.  Notwithstanding  any provision to the
         contrary herein, Purchaser's obligations under this Section 4.4.4 shall
         survive the  expiration or  termination  of this  Agreement,  and shall
         survive Closing.

                  4.4.5 No Covenants. Notwithstanding anything in this Agreement
         to  the  contrary,   the  approvals,   consents  and  releases  of  the
         obligations  of Purchaser and Seller  relating to the Bonds as referred
         to in Sections 4.4.2 and 4.4.3 hereof are only conditions  precedent to
         the  Closing  of  the  transaction  contemplated  hereby,  and  neither
         Purchaser nor Seller covenant that such approvals, consents or releases
         can or will be obtained. Failure to obtain such approvals,  consents or
         releases  shall  not  constitute  a  breach  by  either  party  of this
         Agreement,  the sole and  exclusive  remedy  of  either  party for such
         failure being  termination of this Agreement,  subject to the Surviving
         Covenants, and return to Purchaser of the Deposit.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 16






         4.5 Evidence of Authority;  Miscellaneous. Both parties will deliver to
the Title Company and each other such evidence or documents as may reasonably be
required by the Title  Company or either party hereto  evidencing  the power and
authority of Seller and  Purchaser  and the due  authority of, and execution and
delivery  by, any  person or  persons  who are  executing  any of the  documents
required  hereunder in connection  with the sale of the  Property.  Both parties
will execute and deliver  such other  documents  as are  reasonably  required to
effect the intent of this Agreement.

         4.6 Assignment and  Assumption of Partnership  Interests in Seller.  In
lieu of purchasing the Property as set forth herein,  at Closing,  Purchaser may
elect to purchase one hundred  percent  (100%) of the  partnership  interests in
Seller (the "Partnership  Interests")  pursuant to the Assignment and Assumption
of Partnership  Interests  attached hereto as Exhibit O. If Purchaser  elects to
purchase the Partnership Interests,  as a condition precedent to Closing, Seller
shall deliver to Purchaser evidence that Seller's partners have consented to the
assignment and assumption by Purchaser of the Partnership Interests.

                                    Article V
                        Prorations of Rents, Taxes, Etc.

         All  revenues,  taxes  and  other  expenses  of the  Property  shall be
prorated at Closing as of 12:01 a.m. on the Closing Date.  Real estate taxes for
the year of Closing  shall be  prorated as of the date of Closing  either  using
actual tax figures or, if actual figures are not available, then using



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 17






as a basis  for  said  proration  the  most  recent  assessed  value of the Real
Property  multiplied by the current tax rate,  with a subsequent cash adjustment
to be made between  Purchaser and Seller  outside escrow when actual tax figures
are  available,  but in no event later than the date which is 120 days after the
Closing Date (the "Final  Settlement  Date).  Personal  property  taxes,  annual
permit or inspection  fees,  sewer  charges,  and other  expenses  normal to the
operation and  maintenance of the Property shall also be prorated as of the date
of Closing, either using actual figures or, if actual figures are not available,
then using good faith  estimates,  with a subsequent  cash adjustment to be made
between  Purchaser and Seller outside closing when actual figures are available,
but in no event later than the Final  Settlement  Date.  Rents and other  income
that have been  collected  for the month of the Closing  will be prorated at the
Closing,  effective as of 12:01 a.m. on the Closing Date.  Interest on the Bonds
shall be prorated as of the Closing and an appropriate adjustment shall be made.
Seller  shall  receive a credit  for all funds in (i) the debt  service  reserve
escrow  account with regard to the Bonds,  and (ii) the cash  collateral  escrow
account with regard to the Bonds. With regard to rents that are delinquent as of
the date of the  Closing,  (i) no proration  will be made at the  Closing,  (ii)
Purchaser  will make a good faith  effort after the Closing to collect the rents
in the  usual  course  of  Purchaser's  operation  of the  Property,  and  (iii)
Purchaser  will apply all rents  collected  first to the rents owed to Purchaser
for periods  after the  Closing,  and the excess  amount,  if any,  collected by
Purchaser  within 120 days after Closing shall be applied to the delinquent rent
owed to Seller. It is agreed,  however,  that Purchaser will not be obligated to
institute  any  lawsuit or other  collection  procedures  to collect  delinquent
rents.  Rents collected by Purchaser  within 120 days after the Closing Date, to
which Seller is entitled,  shall be promptly  paid to Seller.  As of the Closing
Date, Purchaser shall be



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 18






entitled to a credit for any tenant  deposits  under the Leases,  together  with
interest  thereon to the extent any  interest is required by law or otherwise to
be paid to such tenants.  Final readings on all gas,  water and electric  meters
shall be made as of the Closing  Date,  if possible.  If final  readings are not
possible,  gas, water and electricity charges will be prorated based on the most
recent  period for which costs are  available.  Any deposits made by Seller with
utility  companies  shall be returned to Seller.  Purchaser shall be responsible
for making all arrangements for the continuation of utility services.  After the
Closing, Purchaser will assume full responsibility for all security deposits and
advance rental deposits of current  tenants of the Real Property  currently held
by Seller,  which items will be itemized by Seller and transferred and paid over
to Purchaser at the Closing.

         All  items  (including   taxes)  that  are  not  subject  to  an  exact
determination shall be estimated by the parties.  When any item so estimated is,
after the Closing capable of exact determination, but in no event later than the
Final  Settlement  Date, the party in possession of the facts  necessary to make
the  determination  shall send the other  party a  detailed  report on the exact
determination  so made and the parties  shall adjust the prior  estimate  within
thirty (30) days after both parties have received said reports.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 19






                                   Article VI
                     Purchaser Inspections and Contingencies

         6.1  Document  Inspection.   Purchaser  acknowledges  that  Seller  has
delivered , to the extent in the  possession  of Seller for review by Purchaser,
the items or  materials  listed on  Exhibit I  attached  hereto  and made a part
hereof, other than the Title Commitment (as hereinafter defined), the Supporting
Documents (as hereinafter  defined),  and the Survey (as hereinafter  defined) (
such items except for the Title Commitment,  the Supporting  Documents,  and the
Survey  are   hereinafter   referred  to  collectively  as  the  "DUE  DILIGENCE
MATERIALS"). In the event Seller obtains after the Effective Date any additional
items or materials which are included within the categories contained in Exhibit
I, copies of such items or materials shall be promptly delivered to Purchaser.

         Purchaser agrees that if for any reason the Closing is not consummated,
Purchaser will immediately  return to Seller any and all materials  furnished to
Purchaser  pursuant to this Section 6.1 or otherwise  obtained by Purchaser with
respect to the Property.

         Purchaser  acknowledges  and agrees that Seller's  having  delivered or
made available to Purchaser the foregoing  items in accordance with this Section
6.1  constitutes  a good  faith  undertaking  only,  and does not  constitute  a
representation  or  warranty  on the part of Seller  with  respect to any of the
foregoing  or  with  respect  to the  accuracy  of the  materials  furnished  to
Purchaser.



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 20






         6.2 Physical Inspection.  In addition to Seller's having made available
to Purchaser the Due Diligence Materials, Purchaser acknowledges that Seller has
made the Property  available to Purchaser and Purchaser has  conducted,  or will
during  the  Feasibility  Period  conduct,   at  Purchaser's  risk,  a  Phase  I
environmental   audit  (the   "Environmental   Audit")  of  the  Property.   The
Environmental  Audit  shall  be  conducted  at a  reasonable  times so as not to
interfere with the business of tenants at the Real  Property.  Seller shall have
the right to  designate a  representative  to accompany  Purchaser's  employees,
agents, and independent contractors on any such Environmental Audit.

         Purchaser  hereby agrees to pay,  protect,  defend,  indemnify and save
Seller  harmless  against  all  liabilities,   obligations,   claims  (including
mechanic's lien claims), damages,  penalties, causes of action, judgments, costs
and expenses  (including,  without  limitation,  reasonable  attorneys' fees and
expenses) imposed upon,  incurred by or asserted against Seller involving either
bodily injury or property  damage in connection with or arising out of the entry
upon the Real Property,  either prior to or after execution and delivery of this
Agreement and caused by Purchaser's employees, agents or independent contractors
and the actions of such persons on the Real  Property.  In the event any part of
the Property is or has been damaged or excavated by  Purchaser,  its  employees,
agents or independent  contractors,  Purchaser  agrees in the event its purchase
hereunder is not consummated,  to make such additional payments to Seller as may
be reasonably required to return the Property to its condition immediately prior
to such damage or excavation  or, at Seller's  option,  to cause such work to be
done. Notwithstanding any provision



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 21






to the contrary herein,  Purchaser's  obligations under this subparagraph  shall
survive the  expiration  or  termination  of this  Agreement,  and shall survive
Closing.

         6.3 Feasibility  Period.  Purchaser shall have the period from February
22, 1999 until 5:00 p.m. E.S.T. on March 8, 1999 (the  "FEASIBILITY  PERIOD") to
conduct its inspection of the Due Diligence Materials. On or before the last day
of the  Feasibility  Period,  Purchaser  may,  in its  sole  discretion  without
obligation  to  specify  which  aspect  of its  inspection  was  unsatisfactory,
terminate  this Agreement by delivering a written notice to Seller so providing.
Upon receipt of such notice,  this  Agreement  shall  terminate and Seller shall
instruct the Title Company to return the Deposit to Purchaser, and neither party
shall have any obligation to the other, except for the Surviving  Covenants.  If
Purchaser  fails to deliver such notice of termination on or before the last day
of the  Feasibility  Period,  (a) Purchaser shall be deemed to have approved the
Due  Diligence  Materials,  (b) this  Agreement  shall  remain in full force and
effect,  and  (c) the  Deposit  shall  become  non-refundable,  subject  only to
Purchaser's right to terminate this Agreement as provided in this Agreement.

         6.4 Survey Contingency.  Purchaser shall have until 5:00 p.m.E.S.T.  on
the later of (i) the last day of the Feasibility  Period,  or (ii) ten (10) days
after receipt of the Survey to terminate  this Agreement due to any objection to
the Survey (as defined on Exhibit I) or any information  reflected thereon.  The
Survey and all  information  reflected  thereon shall be deemed  approved in all
respects if Seller has not received  written notice of  Purchaser's  termination
before  such  date.  If  Purchaser  does  terminate  this  Agreement  in writing
delivered prior to the expiration of the



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 22






Feasibility  Period,  Seller  shall  instruct  the Title  Company  to return the
Deposit to  Purchaser,  and neither  party  shall have any  further  obligations
hereunder, except for the Surviving Covenants.

         6.5  Title  Contingency.   It  shall  be  a  condition  to  Purchaser's
obligation  to close  hereunder  that the Title Company issue at Closing an ALTA
Form B  (1970)  Owner's  Title  Insurance  Policy  (or an  equivalent  form  for
Oklahoma) (or a marked-up  commitment therefor) insuring fee simple title to the
Real  Property in Purchaser in the amount of the Purchase  Price subject only to
the Permitted  Exceptions (the "TITLE POLICY"),  containing an extended coverage
endorsement over the so-called  general or standard  exceptions which are a part
of the printed form of the policy (unless the same are deleted),  an endorsement
deleting any  creditors'  rights  exceptions or exclusions (if any appear in the
form of policy to be issued), an owner's comprehensive endorsement, an ACTA Form
3.1 zoning endorsement,  an ACTA Form 9 comprehensive endorsement,  an ACTA Form
8.1  environmental  endorsement,  a survey/location  endorsement,  an access (to
publicly dedicated street)  endorsement,  a contiguity (if more than one parcel)
endorsement,   and  a  tax   parcel   endorsement   (collectively,   the  "Title
Endorsements").  Accordingly,  Purchaser  has  obtained,  or shall,  during  the
Feasibility  Period,  obtain a  commitment  for the  Title  Policy  (the  "TITLE
COMMITMENT"),  issued by the Title Company in the amount of the Purchase  Price,
together  with  copies  of all  items  and  documents  referred  to in the Title
Commitment (the "SUPPORTING DOCUMENTATION").

         Purchaser shall have until 5:00 p.m. E.S.T. on the later of (i) the 
last day of the Feasibility Period, or (ii) ten (10) days after receipt of the 
Title Commitment  to terminate this Agreement



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 23






due to any  objections  to the Title  Commitment  or any  information  reflected
thereon. The Title Commitment,  the Supporting Documentation and all information
reflected  thereon  shall be deemed  approved in all  respects if Seller has not
received written notice of Purchaser's termination of this Agreement before such
date.  Notwithstanding  the foregoing,  provided that Purchaser  notifies Seller
specifically in writing on or before the last day of the  Feasibility  Period as
to the existence of any Removable Liens (defined below),  Seller shall cause the
Title Company to remove (with proceeds of the Purchase Price,  unless  otherwise
provided  by  Seller)  from the  Owner's  Title  Policy all  monetary  liens and
encumbrances  affecting the Property,  other than liens associated with the Bond
Financing  and  liens for  current  taxes  not yet due and  payable  ("REMOVABLE
LIENS").  If Purchaser does terminate this Agreement in writing  delivered prior
to the  expiration of the  Feasibility  Period,  then Seller shall  instruct the
Title Company to return the Deposit to  Purchaser,  and neither party shall have
any further obligations hereunder, except for the Surviving Covenants.



                                   Article VII
                      Loss due to Casualty or Condemnation

         7.1 Loss due to Condemnation.  In the event of a condemnation of all or
a  Substantial  Portion  (hereinafter   defined)  of  the  Real  Property  which
condemnation  shall or would render a  Substantial  Portion of the Real Property
untenantable, or if any portion of the building or



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 24






substantial  parking area is taken, or if the existing access to the Property is
materially  altered or restricted in any way, Purchaser may, upon written notice
to Seller  given  within ten (10)  Business  Days (as  hereinafter  defined)  of
receipt of notice of such event, terminate this Agreement, in which event Seller
shall  instruct  the Title  Company to return the  Deposit  to  Purchaser,  this
Agreement shall terminate and neither party shall have any rights or obligations
hereunder,  except for the  Surviving  Covenants.  In the event  that  Purchaser
elects not to terminate,  or if the condemnation affects less than a Substantial
Portion or does not affect the building or substantial  parking area,  then this
Agreement shall remain in full force and effect, and Seller shall be entitled to
all  monies  received  or  collected  by  reason of such  condemnation  prior to
Closing.  In such event,  the  transaction  hereby  contemplated  shall close in
accordance  with the terms and  conditions of this  Agreement  except that there
will be an  abatement  of the  Purchase  Price  equal to the  amount  of the net
proceeds (less costs and attorneys fees), which are received by Seller by reason
of such condemnation prior to Closing. If the condemnation  proceeding shall not
have been  concluded and no  condemnation  proceeds have been paid to or for the
benefit of Seller prior to the Closing,  then there shall be no abatement of the
Purchase  Price and Seller shall assign any interest it has in the pending award
to Purchaser. For purposes of this Section 7.1, a Substantial Portion shall mean
a condemnation of in excess of $100,000 in value of the Real Property.

         7.2 Loss due to Casualty.  In the event of  Substantial  Loss or Damage
(hereinafter  defined)  to the  Real  Property  by fire or other  casualty  (not
resulting  from acts of Purchaser or its agents),  Purchaser  may,  upon written
notice to Seller  given  within ten (10)  Business  Days of receipt of notice of
such event, terminate this Agreement in which event Seller shall instruct the



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 25






Title  Company  to return the  Deposit to  Purchaser  and this  Agreement  shall
terminate  and  neither  party shall have any rights or  obligations  hereunder,
except for the Surviving  Covenants.  In the event that Purchaser  elects not to
terminate,  or if the casualty  results in less than Substantial Loss or Damage,
then this  Agreement  shall  remain in full force and effect and Seller shall be
entitled  to all  insurance  proceeds  received or  collected  by reason of such
damage or loss,  whereupon the transaction  hereby  contemplated  shall close in
accordance  with the terms and  conditions of this  Agreement  except that there
will be abatement of the Purchase  Price equal to the amount of the net proceeds
plus all deductible  amounts under any applicable  casualty  insurance of Seller
less costs and attorney's fees, which are received by Seller as a result of such
damage or loss,  provided  that such  abatement  will be  reduced  by the amount
expended by Seller in  accordance  with Article VIII hereof for  restoration  or
preservation of the Property  following the casualty.  Alternatively,  Purchaser
may, in its discretion,  have Seller repair or replace the damaged Property, and
there  shall  be no  abatement  of the  Purchase  Price in such  case.  However,
Purchaser  shall  not  be  entitled  to  require  Seller  to  effect  repair  or
replacement  unless the loss is entirely  covered by  insurance  (except for any
applicable  deductible),  Seller is not restricted  from using such proceeds for
repairs  or  restoration  by the  terms  of any  existing  mortgage  or the Bond
Documents, and the repair or replacement will take no more than three (3) months
to complete.  For purposes of this  Section  7.2,  "SUBSTANTIAL  LOSS OR DAMAGE"
shall mean loss or damage, the cost for repair of which exceeds $100,000.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 26






                                  Article VIII
       Seller's Operation and Maintenance of the Property Prior to Closing

         Between the Effective Date of this Agreement and the earlier of (i) the
Closing Date, or (ii) the termination of this  Agreement,  Seller shall maintain
the Property in good repair,  reasonable  wear and tear excepted,  shall perform
all work required to be done under the terms of any lease or agreement  relating
to the Property, and shall timely make all repairs, maintenance and replacements
of equipment  or  improvements,  the same as though  Seller were  retaining  the
Property;  except that in the event of a fire or other casualty, damage or loss,
Seller shall have no duty to repair said damage,  except as set forth in Section
7.2 above.  However,  Seller may repair any such damage with Purchaser's  prior,
written approval and may, without Purchaser's approval, repair damage where such
repair is necessary in Seller's  reasonable  opinion to preserve and protect the
health and safety of tenants of the Property or to preserve  the  Property  from
imminent  risk of further  damage or if required to do so by Seller's  insurance
carrier.  Any such  emergency  repairs shall be reported to Purchaser  within 48
hours of their completion. During the period prior to Closing and after the last
day of the  Feasibility  Period,  Seller shall not lease any portion of the Real
Property except in the ordinary course of business.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 27






                                   Article IX
                                     Broker

         Purchaser and Seller  represent to each other that they have dealt with
no agent or broker who in any way has  participated in the sale of the Property,
except for Case & Associates  Properties,  Inc.  ("Case")  and CB Richard  Ellis
("CB")  (collectively,  the  "BROKERS").  The brokerage fee of one-half  percent
(.5%)  of the  Purchase  Price  owed to Case and the  brokerage  fees of one and
one-quarter  percent (1.25%) owed to CB will be paid by Seller at Closing.  Each
party will indemnify the other for any and all brokerage fees and commissions of
any brokers based on dealings with them other than as provided above.

                                    Article X
                         Representations and Warranties

         10.1 Limitations on  Representations  and Warranties.  Purchaser hereby
agrees and acknowledges that, except as set forth in Section 10.2 below, neither
Seller nor any agent,  attorney,  employee or  representative of Seller has made
any representation  whatsoever regarding the subject matter of this sale, or any
part thereof,  including  (without  limiting the  generality  of the  foregoing)
representations  as to the  physical  nature or condition of the Property or the
capabilities  thereof,  and that  Purchaser,  in  executing,  delivering  and/or
performing this Agreement,  does not rely upon any statement and/or  information
to whomever made or given, directly or indirectly,  orally or in writing, by any
individual, firm or corporation. Purchaser agrees to take the Real



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 28






Property  and the  Personal  Property  "as is," as of the  Effective  Date,
reasonable  wear and tear  excepted.  EXCEPT  AND ONLY TO THE  EXTENT  AS MAY BE
EXPRESSLY  PROVIDED  IN THIS  AGREEMENT,  SELLER  MAKES  NO  REPRESENTATIONS  OR
WARRANTIES  AS TO THE  PHYSICAL  CONDITION  OF THE  PROPERTY OR THE  SUITABILITY
THEREOF FOR ANY PURPOSE FOR WHICH  PURCHASER MAY DESIRE TO USE IT. SELLER HEREBY
EXPRESSLY  DISCLAIMS ANY  WARRANTIES  OF  MERCHANTABILITY  AND/OR  FITNESS FOR A
PARTICULAR  PURPOSE  AND  ANY  OTHER  WARRANTIES  OR  REPRESENTATIONS  AS TO THE
PHYSICAL CONDITION OF THE PROPERTY. PURCHASER, BY ACCEPTANCE OF THE DEED, AGREES
THAT IT HAS  INSPECTED  THE  PROPERTY  AND  ACCEPTS  SAME  "AS-IS" AND "WITH ALL
FAULTS" AND THIS PROVISION SHALL SURVIVE CLOSING AND DELIVERY OF THE DEED.

         Purchaser  understands that Seller makes no representation and warranty
with regard to any financial statements and data, including, without limitation,
gross rental income, operating expenses and cash flow statements relating to the
Property as all such  financial  data and  statements  have been prepared by the
property manager, Case and Associates, which is an affiliate of Purchaser.

         10.2     Representations and Warranties of Seller.  Seller makes the 
following representations and warranties and agrees that Purchaser's obligations
under this Agreement are



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 29






conditioned upon the truth and accuracy of such  representations and warranties,
both as of this date and as of the Closing Date:

Except as may be disclosed in the Due Diligence Materials,

                  (a) To the best of Seller's knowledge,  Seller has received no
         notice   of   any   existing,   pending   or   threatened   litigation,
         administrative proceeding or condemnation or sale in lieu thereof, with
         respect to any portion of the Real Property, except as noted on Exhibit
         J attached hereto.

                  (b) To the best of Seller's knowledge,  Seller has received no
         notice from any governmental authority pertaining to the Real Property.

                  (c) Except for those  tenants and  licensees in  possession of
         the Real Property  under  written  Leases as shown in the Rent Roll (as
         the same  may be  updated  before  Closing),  to the  best of  Seller's
         knowledge,  there are no parties in  possession  of, or, to the best of
         Seller's knowledge, claiming any possession to, any portion of the Real
         Property as lessees, tenants at sufferance,  licensees,  trespassers or
         otherwise.

                  (d) Seller has  delivered  to  Purchaser a true,  complete and
         correct copy of Seller's partnership agreement.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 30






                  (e) There  are no  attachments  or  executions  affecting  the
         Property,   general  assignments  for  the  benefit  of  creditors,  or
         voluntary or involuntary proceedings in bankruptcy,  pending or, to the
         best of Seller's knowledge, threatened against Seller.

                  (f) Except as otherwise  disclosed in the Environmental  Audit
         and except for normal and  customary  use of  Hazardous  Materials  (as
         hereinafter  defined) in the use and  operation  of the Property in the
         ordinary course of business, during the period of Seller's ownership of
         the  Property,  (i) Seller has not itself,  and to the best of Seller's
         knowledge,  no prior owner or current or prior tenant or other occupant
         of all or any part of the  Property  at any time  has,  used  Hazardous
         Materials  on,  from,  or  affecting  the  Property  in any manner that
         violates any Environmental Laws (as hereinafter  defined),  and (ii) to
         the best of  Seller's  knowledge,  no  Hazardous  Materials  have  been
         disposed of in, on or under the Property.  "HAZARDOUS  MATERIALS" shall
         mean and include those elements, materials, compounds, mixtures, wastes
         or substances  which are contained in any list of hazardous  substances
         adopted by the  United  States  Environmental  Protection  Agency  (the
         "EPA") or any list of toxic  pollutants  designated  by Congress or the
         EPA or which are defined as hazardous,  toxic,  pollutant,  infectious,
         flammable or radioactive by any of the Environmental  Laws and, whether
         or not included in such lists,  shall be deemed to include all products
         or substances containing lead, petroleum, asbestos, and polychlorinated
         biphenyls.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 31






                "ENVIRONMENTAL LAWS" shall mean and include any Federal, State,
          or local statute, law, ordinance, code,  rule,  regulation,  order, or
          decree  regulating  or relating to  protection  of human health or the
          environment,  or  regulating  or imposing  liability  or  standards of
          conduct  concerning  the  use,  storage,  treatment,   transportation,
          manufacture,  refinement,  handling,  production  or  disposal  of any
          hazardous,  toxic, or dangerous waste, substance,  element,  compound,
          mixture  or  material,  as now  or at any  time  hereafter  in  effect
          including, without limitation, the Federal Comprehensive Environmental
          Response,  Compensation  and  Liability  Act,  as  amended,  42 U.S.C.
          ss.ss.9601 et seq., the Superfund  Amendments and Reauthorization Act,
          42 U.S.C.  ss.ss.9601 et. seq., the Federal Oil Pollution Act of 1990,
          ss.ss.2701,  et. seq.,  the Federal Toxic  Substances  Control Act, 15
          U.S.C.  ss.ss.2601 et. seq.,  the Federal  Resource  Conservation  and
          Recovery Act as amended,  42 U.S.C.  ss.ss.6901  et. seq., the Federal
          Hazardous Materials Transportation Act, 49 U.S.C. ss.ss.1801 et. seq.,
          the  Federal  Clean Air Act 42 U.S.C.  ss.7401 et.  seq.,  the Federal
          Water Pollution Control Act, 33 U.S.C. ss.1251 et. seq., the River and
          Harbors  Act of 1899,  33 U.S.C.  ss.ss.401  et.  seq.,  all rules and
          regulations  of the EPA,  or any other  state or  federal  department,
          board, or agency, or any other agency or governmental  board or entity
          having  jurisdiction  over the Security,  as any of the foregoing have
          been, or are hereafter amended.

                  (g) Seller has all requisite  partnership  power and authority
         to enter into this Agreement and convey the Property or the Partnership
         Interests,  as applicable,  to Purchaser and to execute and deliver all
         agreements and documents in connection



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 32






         therewith as are  contemplated by this Agreement in accordance with and
         subject to the terms and  conditions  of this  Agreement.  Neither  the
         delivery of this Agreement nor its  performance  by Seller,  subject to
         obtaining the Bond Consents, will conflict with or result in the breach
         of any contract, agreement, law, rule, regulation,  judgment or lien to
         which Seller is a party or by which Seller is bound.

                  (h) This  Agreement  and its  performance  by Seller have been
         duly  authorized by all  necessary  partnership  action under  Seller's
         partnership agreement.

         10.3  Seller's  Knowledge.  Whenever  the term "to the best of Seller's
knowledge" is used in this  Agreement or in any  representations  and warranties
given to Purchaser at Closing,  such knowledge shall be the actual  knowledge of
John D. Carey (the "Key Personnel") who is President of CIGNA Realty  Resources,
Inc. - Fifth,  the sole general partner of Connecticut  General Realty Investors
III Limited  Partnership  ("CGRI III"),  the managing  partner of Seller,  after
review of the files of Seller (to the extent within the possession or control of
CGRI III), and inquiry of Seller's property  manager.  Seller shall have no duty
to  conduct  any  further  inquiry  in  making  any  such   representations  and
warranties,  and no  knowledge of any other person shall be imputed to Seller or
to the Key Personnel.

         10.4     Representations and Warranties of Purchaser.  Purchaser makes 
the following representations and warranties and agrees that Seller's 
obligations under this Agreement are



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 33






conditioned upon the truth and accuracy of such  representations and warranties,
both as of this date and as of the Closing Date:

                  (a) Purchaser  has all requisite  power and authority to enter
         into this  Agreement  and  purchase  the  Property  or the  Partnership
         Interests,  as  applicable,  from Seller and to execute and deliver all
         agreements and documents in connection therewith as are contemplated by
         this  Agreement  in  accordance  with  and  subject  to the  terms  and
         conditions  of this  Agreement.  Neither the  execution and delivery of
         this  Agreement nor its  performance by Purchaser will conflict with or
         result  in  the  breach  of  any  contract,  agreement,  law,  rule  or
         regulation  to which  Purchaser  is a party or by  which  Purchaser  is
         bound; and

                  (b) This  Agreement has been duly  authorized by all necessary
         action on the part of Purchaser.

         10.5 Survival.  All representations and warranties contained in Section
10.2 will survive the Closing of this  transaction (but only as to the status of
facts as they exist as of the Closing,  it being understood that Seller makes no
representations  or  warranties  which would  apply to changes or other  matters
occurring after the Closing), but shall expire on the date one (1) year from the
date of Closing,  and no action on such  representations  and  warranties may be
commenced after such expiration.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 34






                                   Article XI
                               Liability of Seller

         Except for any  liability of Seller under the  provisions of Article X,
neither Seller, nor any partner of Seller, nor any independent  property manager
which  Seller has hired to manage the  Property  shall,  by  entering  into this
Agreement,  become  liable  for any  costs or  expenses  incurred  by  Purchaser
subsequent to the date of Closing,  (a) for any labor performed on, or materials
furnished  to, the Real  Property on or after the Closing  Date,  or (b) for any
leasing  commissions or other fees or commissions due for renewals or extensions
of  existing  leases or  otherwise  renewed or extended  after the Closing  Date
(unless the existence of such commissions or fees was not disclosed to Purchaser
in this  Agreement  or in the Due  Diligence  Materials  or  otherwise,  (c) for
compliance with any laws, requirements or regulations of, or taxes,  assessments
or other charges  thereafter due to, any  governmental  authority and related to
events  first  occurring  on or after the  Closing  Date,  or (d) under the Bond
Documents and relating to obligations thereunder related to periods on and after
the Closing Date, or (e) for any other charges or expenses whatsoever pertaining
to the Property or to the ownership, title, possession, use, or occupancy of the
Property,  whether or not such costs and  expenses  were  incurred  pursuant  to
obligations of Purchaser under this Agreement  (including,  without  limitation,
any costs of compliance with  presently-existing  and future environmental laws,
any environmental remediation costs, and any costs of, or awards of damages for,
damage to the  environment,  to natural  resources,  or to any third party),  it
being the intent of this Agreement\,  as between  Purchaser and Seller, to shift
all such liability to Purchaser for liabilities which arise from or relate to an
event first occurring from



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 35






and after  the  Closing  Date,  except  for any  liability  of Seller  under the
provisions of Article X hereof, and Purchaser hereby agrees to defend, indemnify
and hold Seller and its property  manager  harmless from any such  liability for
costs and expenses.  The  provisions  of this Article XI shall survive  Closing.
Except as may be specifically limited herein,  nothing contained in this Article
XI is in any way  intended to limit any rights of the  parties  hereto to pursue
any  remedies  as may  exist at law or in equity  against  any  unrelated  third
parties with respect to the liabilities covered by this Article XI.

                                   Article XII
                                   Assignment

         This  Agreement is solely for the benefit of Seller and  Purchaser  and
there are no third-party  beneficiaries  hereof.  Neither this Agreement nor any
interest  hereunder  shall be assigned or  transferred  by Seller or  Purchaser,
except as  expressly  provided  herein.  Notwithstanding  the  foregoing  to the
contrary,  Purchaser  shall  have the  right to  assign  all of its  rights  and
interests  in this  Agreement  at or prior to Closing to an entity  which has an
affiliate of Purchaser as its general partner or managing member,  as applicable
(the "Permitted  Assignee").  Any such permitted assignment shall be effectuated
only by Purchaser signing and causing the Permitted Assignee to sign and deliver
to  Seller  at or prior to the  Closing  Date,  an  assignment,  assumption  and
amendment  agreement in the form attached hereto as Exhibit K. In the event that
this  Agreement  shall be assigned by Purchaser in accordance  with this Article
XII, all of the exhibits and attachments attached hereto shall be deemed revised
to reference the Permitted Assignee as the



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 36






transferee  of the  Property  and  such  documents  shall  be  executed  by such
Permitted Assignee for the purposes of Closing as if Permitted Assignee had been
originally  contemplated  thereby. Any assignment of this Agreement in violation
of the foregoing provisions shall be null and void.

         As used  herein,  an entity  shall be deemed  to be an  "affiliate"  of
Purchaser if such entity is either  controlled  by, under common control with or
controls Purchaser.

         As used herein,  the term "control" and  "controlled by" shall mean the
possession,  directly  or  indirectly,  of the  power to  direct  or  cause  the
direction  of the  management  and policies of such entity  whether  through the
ownership of voting securities, by contract, or otherwise.

                                  Article XIII
                                     Notices
         All  notices  hereunder  or  required  by law shall be sent via  United
States Mail,  postage  prepaid,  certified or registered  mail,  return  receipt
requested,  via facsimile transmission (with a copy sent by United States Mail),
or via any nationally  recognized  commercial  overnight carrier with provisions
for receipt,  addressed to the parties hereto at their respective  addresses set
forth below or as they have theretofore specified by written notice delivered in
accordance herewith:

PURCHASER:                                      Case Ventures, Inc.
                                                4200 East Skelly Drive
                                                Suite 800
                                                Tulsa, OK  74135-3237
                                                Attn:  Mike D. Case
                                                Facsimile:  918.492.4446





                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 37







with a copy to:               Riggs, Abney, Neal, Turpen, Orbison & Lewis, P.C.
                              Frisco Building
                              502 West Sixth Street
                              Tulsa, OK  74119-1010
                              Attn:  Gary Neal, Esq.
                              Facsimile:  918.587.2150

SELLER:                       Waterford Partnership
                              c/o CIGNA Investments, Inc.
                              900 Cottage Grove Road
                              Hartford, CT 06152-2311
                              Attn:  Real Estate Investment Department
                                     Asset Management, S-311
                                     Mr. John D. Carey
                              Facsimile: (860) 726-6327

with a copy to:               CIGNA Corporation
                              900 Cottage Grove Road
                              Hartford, CT 06152-2215
                              Attn:  Investment Law, S-215A
                                     Andrea F. Levy, Esq.
                              Facsimile:  (860) 726-8446



Delivery  will be deemed  complete  upon  actual  receipt  or  refusal to accept
delivery.

                                   Article XIV
                                    Expenses

         Seller  shall  pay  its  own  attorney's   fees   (including,   without
limitation,  the fees of its bond counsel).  Seller shall also pay (i) the title
insurance  premiums  for the  Title  Policy  (including  the cost  for  extended
coverage, ALTA or otherwise),  (ii) the costs of the Survey, (iii) the brokerage
fees  described  in  Article  IX  hereof,  and  (iv) the  costs  of the  termite
certificate described in



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 38






Section 4.2.  Purchaser shall pay (i) all recording costs, (ii) all fees, costs,
and  expenses  incurred by Purchaser  in the conduct and  completion  of its due
diligence  review,  and with respect to the Bonds,  the Bond Financing,  and any
consents,  amendments,  opinions or other  documentation  required in connection
with the satisfaction by Purchaser of the conditions of Sections 4.4.2 and 4.4.3
hereof and its covenants  hereunder,  including without limitation,  the fees of
the  Issuer,  the  Trustee,  and  their  respective  counsel  (but not  Seller's
counsel),  (iii) the cost of the Title  Endorsements,  (iv) any applicable sales
tax on the  transfer of  personal  property,  (v) all revenue  stamps and filing
fees,  and (vi)  any  other  costs  customarily  paid by  purchasers  in  Tulsa,
Oklahoma.  The cost of all closing escrow fees shall be divided  equally between
Seller and Purchaser.

                                   Article XV
                                  Miscellaneous

         15.1  Successors  and  Assigns.  All the terms and  conditions  of this
Agreement  are hereby made binding upon the  executors,  heirs,  administrators,
successors and permitted assigns of both parties hereto.

         15.2 Gender.  Words of any gender used in this Agreement  shall be held
and  construed to include any other  gender,  and words in the  singular  number
shall be held to include the plural, and vice versa, unless the context requires
otherwise.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 39






         15.3 Captions. The captions in this Agreement are inserted only for the
purpose of  convenient  reference  and in no way define,  limit or prescribe the
scope or intent of this Agreement or any part hereof.

         15.4 Construction. No provision of this Agreement shall be construed by
any Court or other judicial authority against any party hereto by reason of such
party's being deemed to have drafted or structured such provisions.

         15.5 Entire Agreement.  This Agreement  constitutes the entire contract
between  the  parties  hereto and there are no other  oral or written  promises,
conditions,  representations,  understandings or terms of any kind as conditions
or inducements to the execution  hereof and none have been relied upon by either
party.  This  agreement  supersedes  any and all  communications,  writings  and
agreements between Purchaser and Seller with respect to the Property,  including
without  limitation,  that certain Letter  Agreement  dated February 9, 1999 and
executed by Purchaser on February 11, 1999, as the same may have been amended in
writing  from time to time which shall be of no further  force and effect  after
the Effective Date.

         15.6  Recording.  The parties  agree that this  Agreement  shall not be
recorded. If Purchaser causes this Agreement or any notice or memorandum thereof
to be  recorded,  this  Agreement  shall be null and void at the  option  of the
Seller.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 40






         15.7 No  Continuance.  Purchaser  acknowledges  that there  shall be no
assignment,  transfer or continuance of any of Seller's insurance coverage or of
the property management contract.

         15.8     Time of Essence.  Time is of the essence in this transaction.

         15.9  Counterparts.  This  Agreement  may be  executed in any number of
identical counterparts,  any or all of which may contain the signatures of fewer
than all of the  parties  but all of which  shall be taken  together as a single
instrument.

         15.10 Governing Law. This Agreement shall be construed,  and the rights
and  obligations  of Seller and  Purchaser  hereunder,  shall be  determined  in
accordance with the laws of the State of Oklahoma.

         15.11 Acceptance of Offer. This Agreement constitutes Seller's offer to
sell to  Purchaser  on the  terms  set  forth  herein  and must be  accepted  by
Purchaser by signing three (3) copies hereof and forwarding all three (3) copies
to the Title Company along with the Deposit in accordance with Article II hereof
no later than 5:00 p.m. EST on March 9, 1999. If Purchaser has not accepted this
Agreement by such date,  then this  Agreement and the offer  represented  hereby
shall automatically be revoked and shall be of no further force or effect.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 41






         15.12  Confidentiality.  Except to the extent disclosure is required by
law,  Purchaser and Seller agree that all documents and  information  concerning
the Property delivered to Purchaser,  the subject matter of this Agreement,  the
result of Purchaser's  inspection and all negotiations will remain confidential.
Purchaser  and Seller  will  disclose  such  information  only to those  parties
required to know it, including,  without limitation,  employees of either of the
parties,  consultants  and  attorneys  engaged  by  either of the  parties,  and
prospective or existing investors and lenders.

         15.13 Surviving Covenants. Notwithstanding any provisions hereof to the
contrary,  the  provisions  of Section  4.4.4  hereof,  the second  paragraph of
Section 6.2 hereof,  the  provisions  of Article IX hereof,  the  provisions  of
Section 15.12  (Confidentiality)  hereof and any other provision which expressly
states  by its  terms  that it  shall  survive  Closing  or the  termination  or
expiration of this Agreement  (collectively,  the "SURVIVING  COVENANTS")  shall
survive the Closing and any  termination  or  expiration of this  Agreement.  In
addition,  the  provisions  of Article X shall survive the Closing to the extent
provided herein.

         15.14  Real  Estate  Reporting  Person.  Seller  and  Purchaser  hereby
designate  Title  Company as the Real Estate  Reporting  Person for  purposes of
Section 6045 of the Internal  Revenue Code, and Title Company,  by its execution
below, hereby accepts such appointment.

         15.15 Independent Contract  Consideration.  Purchaser tenders to Seller
and Seller  acknowledges  receipt of the sum of One Hundred Dollars ($100.00) as
independent  and   non-refundable   contract   consideration  (the  "INDEPENDENT
CONSIDERATION") for any options granted in



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 42






this  Agreement.  The  Independent  Consideration  is in  addition  to any other
deposits  made  under  this  Agreement;  provided,  if  this  Agreement  closes,
Purchaser  will receive a credit against the Purchase Price in the amount of the
Independent Consideration.

         15.16 Exclusive  Period.  Seller agrees that from the Effective Date of
this  Agreement  until the Closing or any earlier  termination of this Agreement
for any reason,  Seller shall not offer the  Property (or any interest  therein)
for sale or lease to any other  party or  negotiate,  solicit or  entertain  any
offers to purchase or lease the Property (or any interest therein).

         15.17 Approval.  Seller's obligation to perform its duties hereunder is
contingent  upon  approval by all required  boards and  committees in accordance
with standard policies and procedures of Seller. Seller will seek such approvals
during the period commencing on the Effective Date hereof to and including March
16, 1999, and will notify Purchaser  promptly of the decision of such boards and
committees.  If the transaction is not approved,  then Seller may terminate this
Agreement by giving notice thereof to Purchaser,  whereupon the Deposit shall be
returned to Purchaser, and neither party shall have any further rights or duties
hereunder except for the Surviving Covenants.

         15.18 Business  Day(s).  As used in this Agreement,  the term "Business
Day(s)"  shall  mean  any day  other  than a  Saturday  or  Sunday  or day  that
commercial  banks are closed for  business in the State of Oklahoma or the State
of Connecticut.




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 43






                            [SIGNATURES ON NEXT PAGE]



                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 44






EXECUTED BY PURCHASER this 8th day of March, 1999.

                    PURCHASER:

                    CASE VENTURES, INC., an Oklahoma corporation


                    By:      /s/ Ben Abney                                     
                             Name:    Ben Abney
                             Its:     Vice President


EXECUTED BY SELLER this _____ day of March, 1999.

                   SELLER:

                   WATERFORD PARTNERSHIP, a Connecticut general
                   partnership

                   By:      Connecticut General Realty Investors III Limited
                            Partnership, a Connecticut limited partnership, its
                            managing general partner

                            By:      CIGNA Realty Resources, Inc. - Fifth, a
                                     Delaware corporation, its sole general
                                     partner

                                     By:      /s/ John D. Carey                
                                              John D. Carey
                                              President


Receipt of original copies of this Agreement executed by Seller and Purchaser is
acknowledged this 8th day of March, 1999.

                            TITLE COMPANY:

                            FRISCO TITLE CORPORATION


                            By:      /s/ M. Jean Little                        
                                     Name: M. Jean Little
                                     Title: Executive Vice President




                  AFL\WATERFRD\P&SIGMOID.005 (3-5-99) Page 45