1. Variational Methods in Electromagnetic Theory;Jones,1977
2. Antennas and Wave Propagation;Collin,1985
3. Mathematical Theory of Optics;Luneburg;Brown University Lecture Notes,1944
4. Geometrical theory of diffraction;Keller;J. Optical Soc. Amer.,1962
5. Electromagnetic theory and Geometrical Optics;Klein,1964