1. A. I. Yakimov, V. A. Markov, A. V. Dvurechenskii, and O. P. Pchelyakov, Philos. Mag. 65, 701 (1992).
2. N. N. Ledentsov, V. M. Ustinov, V. A. Shchukin, et al., Fiz. Tekh. Poluprovodn. (St. Petersburg) 32, 385 (1998) [Semiconductors 32, 343 (1998)].
3. A. V. Dvurechenskii and A. I. Yakimov, Izv. Vyssh. Ucheb. Zaved., Mater. Élektron. Tekh. 4, 4 (1999).
4. A. I. Yakimov, V. A. Markov, A. V. Dvurechenskii, and O. P. Pchelyakov, J. Phys.: Condens. Matter 6, 2573 (1994).
5. Zh. I. Alferov, Fiz. Tekh. Poluprovodn. (St. Petersburg) 32, 3 (1998) [Semiconductors 32, 1 (1998)].