1. A. Scavennec, Opt. Comm., 17, 14 (1976)
2. J. Kluge, D. Wiechert, D. von der Linde, Opt. Comm., 45, 278 (1983)
3. B. Couillaud, V. Fossati-Bellani, Lasers and Appl., 79 and 91 (1985)
4. W.H. Knox, J. Opt. Soc. Am. B4, 1771 (1987)
5. R.L. Fork, B.I. Greene, C.V. Shank, Appl. Phys. Lett., 38, 671 (1981)