[1] S. Pancharman; Proc. Ind. Acad. Sci., 1955, A42, 86.
[3] W. Voigt; Ann. Phys., 1962, 9, 367.
[4] Born and Wolf; Principles of Optics, 1964.
[5] G. A. Massey; IEEE J. Quant. Electr., 1972, QE-8, 669.
[6] J. Junghans et al.; Appl. Opt., 1974, 13, 2793.