1. Assessment of potential unconventional Carboniferous-Permian gas resources of the Liaohe Basin Eastern Uplift, Liaoning Province, China, 2011. [Reston, Va.?] : U.S. Geological Survey, [2012] Book Online
2. Assessment of undiscovered Carboniferous coal-bed gas resources of the Appalachian Basin and the Black Warrior Basin Provinces, 2002 / [by Robert C. Milici and Joseph R. Hatch]. Milici, Robert C., 1931- [Reston, Va.] : U.S. Dept. of the Interior, U.S. Geological Survey, [2004] Book Online