Johnson, William D.
The square buttes coal field Oliver and mercer counties North Dakota / by William D. Johnson and Robert P. Kunkel. -- Washington : United States Government Printing Office, 1959 - 90 p. + map. -- (Geological Survey Bulletin ; 1076).
Dakota del Norte
Rocas carboníferas
552.57(784)
The square buttes coal field Oliver and mercer counties North Dakota / by William D. Johnson and Robert P. Kunkel. -- Washington : United States Government Printing Office, 1959 - 90 p. + map. -- (Geological Survey Bulletin ; 1076).
Dakota del Norte
Rocas carboníferas
552.57(784)