Não informado. (2001). Annual report of the United States Geological Survey. U.S. Geological Survey.
Citace podle Chicago (17th ed.)Não informado. Annual Report of the United States Geological Survey. Washington: U.S. Geological Survey, 2001.
Citace podle MLA (8th ed.)Não informado. Annual Report of the United States Geological Survey. U.S. Geological Survey, 2001.
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