Não informado. (1976). Illinois Natural History Survey Special Publications. Department of Energy and Natural Resources, Natural History Division.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Illinois Natural History Survey Special Publications. Champaign, Ill: Department of Energy and Natural Resources, Natural History Division, 1976.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Illinois Natural History Survey Special Publications. Department of Energy and Natural Resources, Natural History Division, 1976.
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