Não informado. (1976). Illinois Natural History Survey Special Publications. Department of Energy and Natural Resources, Natural History Division.
Chicago-referens (17:e uppl.)Não informado. Illinois Natural History Survey Special Publications. Champaign, Ill: Department of Energy and Natural Resources, Natural History Division, 1976.
MLA-referens (8:e uppl.)Não informado. Illinois Natural History Survey Special Publications. Department of Energy and Natural Resources, Natural History Division, 1976.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.