Leffler, G. L. (1949). Average prices of gas, water and electric light and power companies in Pennsylvania since 1939.
Dyfyniad Arddull ChicagoLeffler, George Leland. Average Prices of Gas, Water and Electric Light and Power Companies in Pennsylvania Since 1939. State College, Pa, 1949.
Dyfyniad MLALeffler, George Leland. Average Prices of Gas, Water and Electric Light and Power Companies in Pennsylvania Since 1939. 1949.
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