EXHIBIT 99.1

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of OneSource Information Services, Inc.
(the "Company") on Form 10-Q for the period ended March 31, 2003 as filed with
the United States Securities and Exchange Commission on the date hereof (the
"Report"), I, Daniel J. Schimmel, Chief Executive Officer of the Company,
certify, pursuant to 18 U.S.C. section 1350, as adopted pursuant to section 906
of the Sarbanes-Oxley Act of 2002, that to the best of my knowledge:

(1) The Report fully complies with the requirements of section 13(a) or 15(d) of
the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material
respects, the financial condition and results of operations of the Company.

/s/ Daniel J. Schimmel

Daniel J. Schimmel
Chief Executive Officer
May 13, 2003

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