Nelson Horatio Darton: Relations of Tertiary Formations in the Western Nebraska Region. The American Geologist. Bd. 23, Nr. 2, 1899, S. 94 (archive.org)
Nelson Horatio Darton: Preliminary Report on the Geology and Water Resources of Nebraska West of the One Hundred and Third Meridian. U.S. Geological Survey Professional Paper 17. U.S. Geological Survey, Department of the Interior, Washington, D.C. 1903 (online).
Thomas S. Ahlbrandt, S. G. Fryberger, John H. Hanley, J. Platt Bradbury: Geologic and Paleoecologic Studies of the Nebraska Sand Hills. U.S. Geological Survey Professional Paper 1120-A-C. U.S. Geological Survey, Department of the Interior, Washington, D.C. 1980 (online).
