Sec. 501. Mining claims located between July 31, 1939, and January 1, 1953. (a) Force and effect. (b) Labor and improvement. (c) Withdrawal or reservation. 502. Reservation of minerals to the United States; rights of entry, disposition and removal. 503. Reservations required by law; atomic energy materials. 504. Power to make arrangements respecting atomic energy materials as unaffected. 505. “Mineral leasing laws” defined.