Não informado. (1970). National Parks and Conservation Magazine. National Parks & Conservation Association.
Chicago-referens (17:e uppl.)Não informado. National Parks and Conservation Magazine. Washington: National Parks & Conservation Association, 1970.
MLA-referens (8:e uppl.)Não informado. National Parks and Conservation Magazine. National Parks & Conservation Association, 1970.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.