Section, acts Aug. 16, 1954, ch. 736, 68A Stat. 211; July 6, 1960, Pub. L. 86–594, § 1, 74 Stat. 333; Sept. 12, 1966, Pub. L. 89–570, § 2(a), 80 Stat. 763; Dec. 30, 1969, Pub. L. 91–172, title V, § 504(a), 83 Stat. 632, related to pre-1970 exploration expenditures.

Repeal effective with respect to taxable years beginning after Dec. 31, 1976, see section 1901(d) of Pub. L. 94–455, set out as an Effective Date of 1976 Amendment note under section 2 of this title.