R. D. Perkins, T. Perry, and D. E. Hattin, “Some Bryozoans from the Beil Limestone Member of the Lecompton Limestone (Virgilian) of Kansas”, kgsbulletin, no. 157, pp. 1–25, Jan. 1962, doi: 10.17161/kgsbulletin.no.i157.22171.