Não informado. (1954). Virginia minerals. Department of Conservation and Development, Division of Geology.
Chicago-referens (17:e uppl.)Não informado. Virginia Minerals. Charlottesville, Va: Department of Conservation and Development, Division of Geology, 1954.
MLA-referens (8:e uppl.)Não informado. Virginia Minerals. Department of Conservation and Development, Division of Geology, 1954.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.