I. G.  Speden, ?The Type Fox Hills Formation, Cretaceous (Maestrichtian), South Dakota. Part 2. Systematics of the Bivalvia?, Peabody Museum of Natural History Bulletin, vol. 33, pp. 1-222, 1970.

I. G.  Speden, ?The Type Fox Hills Formation, Cretaceous (Maestrichtian), South Dakota. Part 2. Systematics of the Bivalvia?, Peabody Museum of Natural History Bulletin, vol. 33, pp. 1-222, 1970.