The Midcontinent Strategic and Critical Minerals Project: Summary and Background Information to Accompany Folio of Maps of the Northern Midcontinent Area, Latitude 36°-46° N. and Longitude 88°-100° W.. 1993-1994
Douglass E. Owen · Kenneth L. Wahl · Walden P. Pratt · Wendell A. Duffield · George N. Breit · John Harvey Sass · Wilbert O. Thomas · M. L. Sorey · Robert M. Hirsch
Jan 1984 · U.S. Government Printing Office