1. L. Brillouin: Ann. Physique (Paris), 9th Ser. 17, 88 (1922)
2. H.A. Lorentz: Wiedman. Ann. 9, 641 (1880)
3. L. Lorenz: Wiedman. Ann. 11, 70 (1881)
4. M. Born, E. Wolf: Principles of Optics, 2nd ed. ( MacMillan, New York 1964 ) p. 87
5. G.R. Fowles: Introduction to Modern Optics (Holt, Rinehart and Winston, New York 1968 ) p. 123