APA (7th ed.) Citation

Harper, J. A., & Laughrey, C. D. (1987). Geology of the oil and gas fields of southwestern Pennsylvania. Commonwealth of Pennsylvania, Dept. of Environmental Resources, Office of Resources Management, Bureau of Topographic and Geologic Survey : May be purchased from State Book Store.

Chicago Style (17th ed.) Citation

Harper, John A., and Christopher D. Laughrey. Geology of the Oil and Gas Fields of Southwestern Pennsylvania. Harrisburg: Commonwealth of Pennsylvania, Dept. of Environmental Resources, Office of Resources Management, Bureau of Topographic and Geologic Survey : May be purchased from State Book Store, 1987.

MLA (9th ed.) Citation

Harper, John A., and Christopher D. Laughrey. Geology of the Oil and Gas Fields of Southwestern Pennsylvania. Commonwealth of Pennsylvania, Dept. of Environmental Resources, Office of Resources Management, Bureau of Topographic and Geologic Survey : May be purchased from State Book Store, 1987.