Sawin, Robert S., Evan K. Franseen, Ronald R. West, Greg A. Ludvigson, and W. Lynn Watney. “Clarification and Changes in Permian Stratigraphic Nomenclature in Kansas”. Current Research in Earth Sciences, no. 254 (September 25, 2008): 1–4. Accessed May 7, 2024. https://journals.ku.edu/cres/article/view/11839.