1. T. V. Krachino, M. V. Kuz’min, M. V. Loginov, and M. A. Mittsev, Fiz. Tverd. Tela (St. Petersburg) 39(9), 1672 (1997) [Phys. Solid State 39, 1493 (1997)].
2. T. V. Krachino, M. V. Kuz’min, M. V. Loginov, and M. A. Mittsev, Fiz. Tverd. Tela (Leningrad) 40(10), 1937 (1998) [Phys. Solid State 40, 1758 (1998)].
3. T. V. Krachino, M. V. Kuz’min, M. V. Loginov, and M. A. Mittsev, Fiz. Tverd. Tela (St. Petersburg) 42(3), 553 (2000) [Phys. Solid State 42, 566 (2000)].
4. S. Yu. Davydov and A. V. Pavlyk, Fiz. Tekh. Poluprovodn. (St. Petersburg) 35(7), 831 (2001) [Semiconductors 35, 796 (2001)].
5. S. Yu. Davydov and I. V. Noskov, Pis’ma Zh. Tekh. Fiz. 27(20), 1 (2001) [Tech. Phys. Lett. 27, 844 (2001)].