1. A. Sommerfeld, “Partial Differential Equations in Physics”, Academic Press, New York, 1949. Sec, 32.
2. L.B. Pelsen and H. Marcuvitz, “Modal Analysis and Synthesis of Electromagnetic Fields”, Microwave Research Institute, Polytechnic Institute of Brooklyn, Report R-726-59, PIB-654, June 1959. Sec.Clb.
3. cf. P.M. Morse and H. Feshbach, “Methods of Theoretical Physics”, McGraw Hill Book Co., New York, 1953, p.766.
4. cf. B. Friedman, “Principles and Techniques of Applied Mathematics”, J.Wiley & Sons, New York, 1956. Ch. 3.
5. N. Marcuvitz and J. Schwinger, “On the Representation of the Electrio and Magnetic Fields…”, J.A.P., 22, June 1951.