Original Silurian and Devonian stratigraphy discussed in Goebel, E.D., 1968, Undifferentiated Silurian and Devonian, in, Zeller, D.E., (ed.); The stratigraphic succession in Kansas: Kansas Geological Survey, Bulletin, no. 189, pp. 15-17 http://www.kgs.ku.edu/Publications/Bulletins/189/05_ordo.html#SILU