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2. Fundamentals of Transmission Lines and Electromagnetic Fields, Addison-Wesley, Reading, MA, p. 149.
3. Modern Optics, John Wiley and Sons, New York, 1990, p. 281.
4. Microwave Engineering, Harcourt Brace Jovanovich, New York, 1989, p. 40.
5. Principles and Applications of Waveguide Transmission, D. Van Nostrand, Princeton, NJ, 1950, p. 167.