Author: Wahlman, G.P., 1992.:
Title: Middle and Upper Ordovician symmetrical univalved mollusks (Monoplacophora and Bellerophontina) of the Cincinnati Arch region. [U.S. Geol. Surv. Prof. Pap., 1066-0.]
Description: Washington 1992. 4to. Pp. xvi,213,[3], numerous photos on 45 plates, 33 figs., refs., index. Orig. wrappers.

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