Principles of electricity and electromagnetism / by, Gaylord Probasco Harnwell. Harnwell, Gaylord Probasco, 1903- Electricity. Electromagnetism. QC518 .H27 1949 538.1 HAP Includes Index. New York : McGraw-Hill Book Co., c1949. c1949. 1949 Text xvi, 670 p. : eng International series in pure and applied physics