1. J. R. Pierce,Traveling Wave Tubes(Van Nostrand, Princeton, NJ, 1950).
2. R. G. E. Hutter,Beam and Wave Electronics in Microwave Tubes(Boston Tech., Cambridge, MA, 1965).
3. Plasma microwave electronics
4. C. C. Johnson,Field and Wave Electrodynamics(McGraw-Hill, New York, 1965), Chap. 9.