U.S. Bureau of Mines. (1965). Mineral facts and problems. s.n.
Lua i Stíl Chicago (17ú heag.)U.S. Bureau of Mines. Mineral Facts and Problems. Washington: s.n, 1965.
Lua MLA (9ú heag.)U.S. Bureau of Mines. Mineral Facts and Problems. s.n, 1965.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.