Kolata, D. R. 1975. Middle Ordovician echinoderms from Northern Illinois and Southern Wisconsin. Journal of Paleontology - The Palaeontological Society Memoir 7, 1-74.
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Kolata, D. R.
1975
Middle Ordovician echinoderms from Northern Illinois and Southern Wisconsin
Journal of Paleontology - The Palaeontological Society Memoir