Não informado. (1973). Journal of research of the United States Geological Survey. U.S. Geological Survey.
Chicago-referens (17:e uppl.)Não informado. Journal of Research of the United States Geological Survey. Washington: U.S. Geological Survey, 1973.
MLA-referens (8:e uppl.)Não informado. Journal of Research of the United States Geological Survey. U.S. Geological Survey, 1973.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.