Stratigraphy and palynology of the Upper Lewis Shale, Pictured Cliffs Sandstone, and Lower Fruitland Formation (Upper Cretaceous) near Durango, Colorado.
Reference:
Manfrino,C. (1984)
Stratigraphy and palynology of the Upper Lewis Shale, Pictured Cliffs Sandstone, and Lower Fruitland Formation (Upper Cretaceous) near Durango, Colorado. The Mountain Geologist
Vol. 21 # 4 P. 115- 132