1. N. V. Agrinskaya, Yu. L. Ivanov, P. A. Petrov, and V. M. Ustinov, Solid State Commun. 126, 369 (2003).
2. B. I. Shklovskiĭ and A. L. Efros, Electronic Properties of Doped Semiconductors (Nauka, Moscow, 1979) [in Russian].
3. P. V. Petrov, Yu. L. Ivanov, and A. E. Zhukov, Fiz. Tekh. Poluprovodn. 41, 850 (2007) [Semiconductors 41, 828 (2007)].
4. N. V. Agrinskaya, Yu. L. Ivanov, V. M. Ustinov, and D. A. Poloskin, Fiz. Tekh. Poluprovodn. 35, 571 (2001) [Semiconductors 35, 550 (2001)].
5. N. S. Averkiev, Yu. L. Ivanov, A. A. Krasivichev, et al., Fiz. Tekh. Poluprovodn. 42, 322 (2008) [Semiconductors 42, 316 (2008)].