As used in this chapter “mineral leasing laws” shall mean the Act of (); the Act of () [ et seq.]; the Act of () [ et seq.]; the Act of () [ et seq.] and all Acts heretofore or hereafter enacted which are amendatory of or supplementary to any of the foregoing Acts.38 Stat. 74141 Stat. 43730 U.S.C. 18144 Stat. 30130 U.S.C. 27144 Stat. 105730 U.S.C. 281October 20, 19141914-10-20February 25, 19201920-02-25April 17, 19261926-04-17February 7, 19271927-02-07