Não informado. (2000). Technical papers. U.S. Department of the Interior, Bureau of Mines.
Chicago-referens (17:e uppl.)Não informado. Technical Papers. Washington: U.S. Department of the Interior, Bureau of Mines, 2000.
MLA-referens (8:e uppl.)Não informado. Technical Papers. U.S. Department of the Interior, Bureau of Mines, 2000.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.