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.
警告：这些引文格式不一定是100％准确.