Baars, D. L., Scott M. Ritter, C. G. Maples, and Charles A. Ross. “Redefinition of the Upper Pennsylvanian Virgilian Series in Kansas”. Bulletin (Kansas Geological Survey), no. 230 (April 16, 2024): 11–16. Accessed July 3, 2024. https://journals.ku.edu/kgsbulletin/article/view/20481.