Não informado. (1964). Commodity Data Summaries. U.S. Department of the Interior, Bureau of Mines.
Chicago-viite (17. p.)Não informado. Commodity Data Summaries. Washington: U.S. Department of the Interior, Bureau of Mines, 1964.
MLA-viite (8. p.)Não informado. Commodity Data Summaries. U.S. Department of the Interior, Bureau of Mines, 1964.
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