APA (7e ed.) Bronvermelding

Leffler, G. L. (1949). Average prices of gas, water and electric light and power companies in Pennsylvania since 1939.

Chicago (17e ed.) Bronvermelding

Leffler, George Leland. Average Prices of Gas, Water and Electric Light and Power Companies in Pennsylvania Since 1939. State College, Pa, 1949.

MLA (8e ed.) Bronvermelding

Leffler, George Leland. Average Prices of Gas, Water and Electric Light and Power Companies in Pennsylvania Since 1939. 1949.