Wheeler, G.M., 1874, Progress report upon geographical and geological explorations and surveys west of the one hundreth meridian, in 1872, under the direction of Brig. Gen A.A. Humphreys, Chief of Engineers, United States Army, by First Lieut. George M. Wheeler, Corps of Engineers, in charge: Washington, D.C., U.S. Government Printing Office, 56 p., 5 sheets.