Não informado. (2009). Mines and Mineral Statistics. Commissioner of Mineral Statistics of the State of Michigan.
Chicago-referens (17:e uppl.)Não informado. Mines and Mineral Statistics. Lansing, Mich: Commissioner of Mineral Statistics of the State of Michigan, 2009.
MLA-referens (8:e uppl.)Não informado. Mines and Mineral Statistics. Commissioner of Mineral Statistics of the State of Michigan, 2009.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.