GLAESSNER, M. F.; BOUCOT, A. J.; JAANUSSEN, Valdar. Part A, Introduction, Ch. 2, p. 79-182. Treatise on Invertebrate Paleontology, [S. l.], 1979. DOI: 10.17161/dt.v0i0.5529. Disponível em: https://journals.ku.edu/InvertebratePaleo/article/view/5529.. Acesso em: 6 may. 2024.