1. Ashcroft, N. W.; Mermin, N. D. (1976): Solid State Physics. Holt, Rinehart & Winston, N. Y.
2. Baer, T. M. (1986): Laser Focus 22, June 86, p. 82
3. Beigang, R.; Litfin, G.; Schneider, R. (1979): Phys. Rev. A 20, 229
4. Beyer, E.; Märten, O.; Behler, K.; Weick, J. M. (1985): Laser und Optoelektronik 3, 282 Bohren, A.; Sigrist, M. W. (1997): Infrared
5. Brown, D. C. (1981): High-Peak-Power Nd: Glass Laser Systems. Springer Series in Optical Sciences, Vol. 25, Springer, Berlin