25 U.S.C. § 96
Section, acts Mar. 3, 1875, ch. 132, §7, 18 Stat. 450; July 31, 1894, ch. 174, §§3, 7, 28 Stat. 205, 206; June 10, 1921, ch. 18, title III, §304, 42 Stat. 24, directed that copies of contracts made by Commissioner of Indian Affairs, or any other officer of Government for the Indian Service, be furnished to General Accounting Office prior to payment.