25 C.F.R. § 213.45
Restricted lands allotted as either homestead or surplus allotments, designated as tax exempt under section 4 of the act of May 10, 1928, as amended May 24, 1928 (45 Stat. 495, 733), the entire interest in which was acquired by inheritance, gift, devise, or purchase with restricted funds, by persons of one-half or more Indian blood, after the passage of the act of January 27, 1933 (47 Stat. 777), continue to be restricted under the provisions of the last mentioned act and oil and gas leases thereof are subject to the regulations in this part and all such leases to be valid must be approved by the Secretary of the Interior. Lands inherited by or devised to full blood Indians prior to the act of January 27, 1933, are not affected as to restrictions by the provisions of said act and may continue to be leased with the approval of the county court having jurisdiction of the estate of the deceased allottee and without approval of the Secretary of the Interior (54 L.D. 382; 10 F. (2d), 487). Lands acquired prior to the passage of the act of January 27, 1933 by Indians of less than full blood, whether such lands were restricted and tax exempt or restricted and taxable, passed to such persons free of all restrictions. Inherited homesteads restricted prior to April 26, 1931, by section 9, of the act of May 27, 1908 (35 Stat. 312), for the benefit of heirs of one-half or more Indian blood but less than full bloods, born after March 4, 1906, became unrestricted April 26, 1931, or upon the death prior thereto of the heir born subsequent to March 4, 1906, and oil and gas leases thereof are not subject to the regulations in this part nor under the jurisdiction of the Secretary of the Interior.
25 C.F.R. §213.45