https://www.usgs.gov/publications/comparative-facies-formation-selected-coal-beds-powder-river-basin
Comparative facies formation in selected coal beds of the Powder River Basin | U.S. Geological...
Petrologic studies of thick coal beds [Warwick, 1985; Moore, 1986; Moore and others, 1986; Moore and others, 1987; Warwick and Stanton, in press], which build...
powder river basincoal bedsof thecomparativefacies