Não informado. (1982). National Water Conditions. U.S. Department of the Interior, Geological Survey.
Chicago-referens (17:e uppl.)Não informado. National Water Conditions. Reston, Va: U.S. Department of the Interior, Geological Survey, 1982.
MLA-referens (8:e uppl.)Não informado. National Water Conditions. U.S. Department of the Interior, Geological Survey, 1982.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.