Boardman , D.R.I. (1994) “Biostratigraphy of Middle and Late Pennsylvanian (Desmoinesian-Virgilian) ammonoids”, Bulletin (Kansas Geological Survey), (232), pp. 1–96. Available at: https://journals.ku.edu/kgsbulletin/article/view/20477 (Accessed: 18 May 2024).