1. Brown University Notes Providence;R. K. Luneberg,1964
2. M. Kline: In The Theory of Electromagnetic Waves (Interscience Publishers Inc., NewYork, 1951), pp. 225–262. See also his chapter in Electromagnetic Waves, ed. by R. E. Langer (University of Wisconsin Press, Madison, 1962), pp. 3–32.
3. M. Kline, I. Kay: Electromagnetic Theory and Geometrical Optics (Interscience Publishers, New York, 1965).
4. J. B. Keller, R. M. Lewis, B. D. Seckler: Comm. Pure Appl. Math. 9, 208 (1973).
5. R. G. Kouyoumjian: Proc. IEEE 53, 864 (1965).