[1]
Kesling, R.V. et al. 1968. Part S, Echinodermata 1, vol. 1 & 2 , Ch. 2, p. 86 - 267. Treatise on Invertebrate Paleontology. (Jan. 1968). DOI:https://doi.org/10.17161/dt.v0i0.5635.