Variations in vitrinite reflectance values for the Upper Cretaceous Mesaverde Formation, Southeastern Piceance Basin, northwestern Colorado : implications for burial history and potential hydrocarbon generation / by Vito F. Nuccio and Ronald C. Johnson. The Fryingpan Member of the Maroon Formation : a Lower Permian(?) basin-margin dune field in northwestern Colorado / by Samuel Y. Johnson.
[Reston, Va.] : Department of the Interior, U.S. Geological Survey, 1989.
[Washington, D.C.] : United States Government Printing Office