1. A. M. Agal’tsov, V. S. Gorelik, and M. M. Sushchinskii, Opt. Spektrosk. 58, 386 (1985) [Opt. Spectrosc. 58, 230 (1985)].
2. A. M. Agaltzov and V. S. Gorelik, J. Russ. Laser Res. 17, 431 (1996).
3. V. A. Babenko, V. S. Gorelik, and A. A. Sychev, J. Russ. Laser Res. 20, 152 (1999).
4. V. S. Gorelik, Izv. Ross. Akad. Nauk, Ser. Fiz. 64, 1181 (2000).
5. A. M. Agal’tsov, V. S. Gorelik, and I. A. Rakhmatullaev, Opt. Spektrosk. 79, 959 (1995) [Opt. Spectrosc. 79, 878 (1995)].