1. N. Bloembergen: Am. J. Phys. 35, 989 (1967)
2. W. Kaiser, M. Maier: In Laser Handbook, Vol. 2, ed. by F.T. Arecchi, E.O. Schulz-Dubois (North-Holland, Amsterdam 1972) Chap. E2
3. A. Penzkofer, A. Laubereau, W. Kaiser: Prog. Quantum Electron. 6, 55 (1979)
4. Y.R. Shen: The Principles of Nonlinear Optics (Wiley, New York 1984)
5. M. Schubert, B. Wilhelmi: Nonlinear Optics and Quantum Electronics (Wiley, New York 1986)