Não informado. (1954). Virginia minerals. Department of Conservation and Development, Division of Geology.
Citação do estilo Chicago (17ª ed.)Não informado. Virginia Minerals. Charlottesville, Va: Department of Conservation and Development, Division of Geology, 1954.
Citação MLA (8ª ed.)Não informado. Virginia Minerals. Department of Conservation and Development, Division of Geology, 1954.
Atenció: Aquestes cites poden no estar 100% correctes.