Fell, H. B., Gerhard Regnéll, R. V. Kesling, R. C. Moore, and Georges Ubaghs. “Part U, Echinodermata 3, Vol. 1 & 2, Ch. 2, P. 108-210”. Treatise on Invertebrate Paleontology (January 1, 1966). Accessed December 13, 2024. https://journals.ku.edu/InvertebratePaleo/article/view/5654.