Ashley, G. H. 1., & Robinson, J. F. (1922). The oil and gas fields of Pennsylvania. Harrisburg: Dept. of Internal Affairs, Bureau of Topographic and Geological Survey.
Chicago Style CitationAshley, Geo. H. 1866-1951., and J. French Robinson. The Oil and Gas Fields of Pennsylvania. Harrisburg: Dept. of Internal Affairs, Bureau of Topographic and Geological Survey, 1922.
MLA CitationAshley, Geo. H. 1866-1951., and J. French Robinson. The Oil and Gas Fields of Pennsylvania. Harrisburg: Dept. of Internal Affairs, Bureau of Topographic and Geological Survey, 1922.