Heckel, P. H., & Watney, W. L. (2002). Revision of Stratigraphic Nomenclature and Classification of the Pleasanton, Kansas City, Lansing, and Lower Part of the Douglas Groups (Lower Upper Pennsylvanian, Missourian) in Kansas. Bulletin (Kansas Geological Survey), 246, 1-139. https://doi.org/10.17161/kgsbulletin.no.246.20392