Moore, R. C., Cox, L. R., Trueman, E. R., Newell, N. D., & Nuttall, C. P. (1969). Part N, Mollusca 6, vol. 1, ch. 1, p. 1–129. Treatise on Invertebrate Paleontology. https://doi.org/10.17161/dt.v0i0.5588