ROSS, Charles A.; KUMMEL, Bernhard; ROSS, June R. P. Part A, Introduction, Ch. 4, p. 291-389. Treatise on Invertebrate Paleontology, [S. l.], 1979. DOI: 10.17161/dt.v0i0.5531. Disponível em: https://journals.ku.edu/InvertebratePaleo/article/view/5531.. Acesso em: 5 may. 2024.