Jope, H. M., A. J. Rowell, Alwyn Williams, and M. J. S. Rudwick. “Part H, Brachiopoda, Vol. 1 & 2, Ch. 2, P. 157-256”. Treatise on Invertebrate Paleontology (January 1, 1965). Accessed May 1, 2024. https://journals.ku.edu/InvertebratePaleo/article/view/5544.