1. I. Nicoara, D. Nicoara, and V. Sofonea, J. Cryst. Growth 104, 169 (1990).
2. E. P. Andreev, E. R. Dobrovinskaya, I. F. Zvyagintseva, et al., Izv. Akad. Nauk SSSR, Ser. Fiz. 47(2), 382 (1983).
3. V. A. Borodin, T. A. Sterepolo, V. A. Tatarchenko, et al., Izv. Akad. Nauk SSSR, Ser. Fiz. 49(12), 2380 (1983).
4. M. I. Musatov and L. I. Belevtseva, Izv. Akad. Nauk SSSR, Neorg. Mater. 12(2), 358 (1976).
5. V. V. Pishchik, Monokrist. Tekh., No. 5, 26 (1972).