Moore, R. C., N. H. Ludbrook, J. Brookes Knight, C. M. Yonge, E. L. Yochelson, and A. G. Smith. 1960. “Part I, Mollusca 1, Ch. 1, p.1-84”. Treatise on Invertebrate Paleontology, January. https://doi.org/10.17161/dt.v0i0.5583.