Melville, R. V., H. B. Fell, P. M. Kier, J. Wyatt Durham, Carol D. Wagner, D. L. Pawson, and A. G. Fischer. 1966. “Part U, Echinodermata 3, Vol. 1 & 2, Ch. 3, P. 211-366”. Treatise on Invertebrate Paleontology, January. https://doi.org/10.17161/dt.v0i0.5655.