«The Magnetic Force of Charles Proteus Steinmetz». IEEE Power Engineering Review. 16 (9): 7. 1996. doi:10.1109/MPER.1996.535476
Bedell, Frederick (1942). «History of A-C Wave Form, Its Determination and Standardization». Transactions of the American Institute of Electrical Engineers. 61 (12): 865. doi:10.1109/T-AIEE.1942.5058456