EXHIBIT 24.13
                                   CERTIFICATE

      I, Lina P. Holm,  Secretary  of Public  Service  Company of  Oklahoma,  an
Oklahoma corporation (the "Corporation"), hereby certify that set forth below is
a complete and  accurate  copy of a certain  resolution  adopted by the Board of
Directors of the  Corporation  on this 18th day of January,  2000, and that such
resolution is in full force and effect as of the date of this certificate.


                       Public Service Company of Oklahoma
                          Board of Directors Resolution
                                January 18, 2000

      RESOLVED,  that each officer of Public Service  Company of Oklahoma listed
at the end of this  sentence  is  hereby  authorized  to  make,  constitute  and
appoint,  in his  respective  capacity,  a power  of  attorney  in  favor of the
person(s)  listed  directly after his name at the end of this  sentence,  as his
true and lawful  attorney(s)-in-fact and agent(s), with full power and authority
(and in the case of more than one attorney-in-fact, each attorney-in-fact acting
alone  and  without  the  other)  to  execute  in the name and on  behalf of the
officer, in any and all capacities, the Corporation's Annual Report on Form 10-K
for 1999 and any and all  amendments  thereto,  to be filed under the Securities
Exchange  Act of 1934,  as  amended,  and any other  documents  and  instruments
incidental  thereto,  and to file the same,  with all  exhibits  thereto and all
documents in connection therewith,  with the Securities and Exchange Commission,
and grant to such  attorney(s)-in-fact,  and  agent(s)  (and in the case of more
than  one  attorney-in-fact,   each  of  them),  full  power  and  authority  of
substitution  and  revocation in the premises and full power and authority to do
and perform each and every act and thing  requisite  and necessary to be done in
and about the  premises,  as fully and all intents  and  purposes as the officer
might or could do in person.

1.    T. D.  Churchwell  is  authorized  to make,  constitute  and  appoint R.
      Russell Davis to be his attorney(s)-in-fact.
2.    R. Russell  Davis is authorized  to make,  constitute  and appoint T. D.
      Churchwell to be his attorney(s)-in-fact.

      IN WITNESS  WHEREOF,  I have  hereunto set my hand and affixed the seal of
Public Service Company of Oklahoma this day, the 18th of January, 2000.



      /s/ Lina P. Holm
          Lina P. Holm





      CORPORATE SEAL