Não informado. (1976). Minerals & Materials. U.S. Department of the Interior, Bureau of Mines.
Chicago-viite (17. p.)Não informado. Minerals & Materials. Washington: U.S. Department of the Interior, Bureau of Mines, 1976.
MLA-viite (8. p.)Não informado. Minerals & Materials. U.S. Department of the Interior, Bureau of Mines, 1976.
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