1. L.F. Johnson, H.J. Guggenheim, R.A. Thomas: Phys. Rev. 149, 179 (1966)
2. P.F. Moulton: In Laser Handbook ed. by M. Bass and M.L. Stick, p 203 ff, Elsevier Science Publishers BV (1985)
3. Tunable Solid State Lasers, Springer Series in Optical Sciences, Vol. 47 ed. by P. Hammerling, A.B. Budgor and A. Pinto 1985
4. Tunable Solid State Lasers, Technical Digest, Zigzag, Oregon (1986), this volume
5. J.A. Caird: talk WA5, this volume