25 U.S. Code § 199 - Access to records of Five Civilized Tribes
The Secretary of the Interior, or his accredited representative, shall at all times have access to any books and records of the Choctaw, Chickasaw, Cherokee, Creek, and Seminole Tribes, whether in possession of any of the officers of either of said tribes or any officer or custodian thereof, of the State of Oklahoma.
For transfer of functions of other officers, employees, and agencies of Department of the Interior, with certain exceptions, to Secretary of the Interior, with power to delegate, see Reorg. Plan No. 3 of 1950, §§ 1, 2, eff. May 24, 1950, 15 F.R. 3174,64 Stat. 1262, set out in the Appendix to Title 5, Government Organization and Employees.