1. I. V. Bykov, E. A. Gan’shina, A. B. Granovskii, and V. S. Gushchin, Fiz. Tverd. Tela (St. Petersburg) 42, 487 (2000) [Phys. Solid State 42, 498 (2000)].
2. A. B. Granovskii, M. Inoue, J. P. Clerc, and A. N. Yurasov, Fiz. Tverd. Tela (St. Petersburg) 46, 484 (2004) [Phys. Solid State 46, 498 (2004)].
3. V. G. Kravets, D. Bozec, J. A. D. Matthew, et al., J. Appl. Phys. 91, 8795 (2002).
4. V. G. Kravets, A. N. Pogorely, A. F. Kravets, et al., Phys. Solid State 45, 1530 (2003).
5. V. G. Kravets and L. V. Poperenko, Opt. Spectrosc. 95, 293 (2003).