Williams, Alwyn, C. C. Emig, M. C. Rhodes, M. A. James, and Sarah Mackay. “Part H, Brachiopoda (Revised), Vol. 1, Ch. 1, P. 1–188”. Treatise on Invertebrate Paleontology (January 1, 1997). Accessed May 6, 2024. https://journals.ku.edu/InvertebratePaleo/article/view/5553.