Não informado. (1954). Virginia minerals. Department of Conservation and Development, Division of Geology.
Citace podle Chicago (17th ed.)Não informado. Virginia Minerals. Charlottesville, Va: Department of Conservation and Development, Division of Geology, 1954.
Citace podle MLA (8th ed.)Não informado. Virginia Minerals. Department of Conservation and Development, Division of Geology, 1954.
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