1. R. A. Hewes and J. F. Sarver, Phys. Rev.,182, No. 2, 427?436 (1969).
2. V. S. Khomenko, N. N. Mit'kina, and V. V. Kuznetsova, Vestsi AN BSSR, Ser. Fiz.-Mat. Nav., No. 6, 89?92 (1976).
3. G. F. Garlick, C. L. Richards, and R. Smith, J. Lumin.,12?13, 707?713 (1976).
4. D. G. Ettinger and T. M. Niemczyk, J. Chem. Phys.,68, No. 3, 872?879 (1978).
5. T. M. Kozhan, V. V. Kuznetsova, I. I. Sergeev, and V. S. Khomenko, Zh. Prikl. Spektrosk.,46, No. 3, 423?427 (1987).