Não informado. (2008). State University of Iowa studies in natural history. State University of Iowa.
Chicago-referens (17:e uppl.)Não informado. State University of Iowa Studies in Natural History. Iowa City, Iowa: State University of Iowa, 2008.
MLA-referens (8:e uppl.)Não informado. State University of Iowa Studies in Natural History. State University of Iowa, 2008.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.