1. John James Stevenson;Berg;Pa. Geol.,1988
2. Notes on the Bernice Anthracite coal-basin, Sullivan County, Pa.;Claghorn;Trans. Am. Inst. Min. Eng.,1889
3. Coalification patterns of Pennsylvania coal basins of the Eastern United States;Damberger,1974
4. The properties of coals as determined by their mode of origin;Hickling;J. Inst. Fuel,1932
5. Die Bezsiehungen zwischen der Zusammensetzung und den technischen Eigenschaften der Steinkohle;Hilt;Ver. Dtsch. Ing. Z.,1873