1. M. Born, E. Wolf: Principles of Optics (Pergamon Press, New York 1975), Chap. 3
2. R.K. Luneburg: Mathematical Theory of Optics (University of California Press, Berkeley 1964), Chaps. 1–3
3. D. Marcuse: Light Transmission Optics, 2nd edn. ( Van Nostrand Reinhold, New York 1982 ), Chap. 1
4. J.A. Arnaud: Beam and Fiber Optics (Academic Press, New York 1976), Chap. 3
5. E.W. Marchand: Gradient Index Optics (Academic Press, New York 1978), Chap. 1 1.6 D.T. Moore: J. Opt. Soc. Am. 65, 451 (1975)