Não informado. (2009). Mines and Mineral Statistics. Commissioner of Mineral Statistics of the State of Michigan.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Mines and Mineral Statistics. Lansing, Mich: Commissioner of Mineral Statistics of the State of Michigan, 2009.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Mines and Mineral Statistics. Commissioner of Mineral Statistics of the State of Michigan, 2009.
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