Não informado. (2001). Bulletin of the Wisconsin Geological and Natural History Survey. Wisconsin Geological and Natural History Survey.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Bulletin of the Wisconsin Geological and Natural History Survey. Madison, Wis: Wisconsin Geological and Natural History Survey, 2001.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Bulletin of the Wisconsin Geological and Natural History Survey. Wisconsin Geological and Natural History Survey, 2001.
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