Sawin, Robert S., and Ronald R. West. “Paleoecology of the Permian (Wolfcampian) Phylloid Alga Calcipatera from an In Situ Occurrence in Kansas, U.S.A”. Current Research in Earth Sciences, no. 251, Feb. 2005, pp. 1-14, https://doi.org/10.17161/cres.v0i251.11835.