1. “Organic-rich Shale of the United States and World Land Areas”;Duncan;U.S. Geol. Surv. Circ,1965
2. “Origin and Microfossils of the Oil Shale of the Green River Formation of Colorado and Utah”;Bradley;U.S. Geol. Surv. Profess. Pap.,1931
3. “Geology and Oil Shale Resources of the Eastern Side of the Piceance Creek Basin, Rio Blanco and Garfield Counties, Colorado”;Duncan;U.S. Geol. Surv. Map, OM,1950
4. “Geology of the Cathedral Bluffs Area, Rio Blanco and Garfield Counties, Colorado”;Donnell;U.S. Geol. Surv. Map, OM,1953
5. “Limnology and the Eocene Lakes of the Rocky Mountain Region”;Bradley;Bull. Geol. Soc. Am.,1948