Não informado. (1940). Special Scientific Report. U.S. Fish and Wildlife Service.
Chicago-referens (17:e uppl.)Não informado. Special Scientific Report. Seattle, Wash: U.S. Fish and Wildlife Service, 1940.
MLA-referens (8:e uppl.)Não informado. Special Scientific Report. U.S. Fish and Wildlife Service, 1940.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.