Παραπομπή σε μορφή APA (7η εκδ.)

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

Παραπομπή σε μορφή Chicago (17η εκδ.)

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

Παραπομπή σε μορφή MLA (8th εκδ.)

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