1. D. C. Chemla, P. J. Kupecek, D. C. Robertson, and R. C. Smith, Opt. Commun. 3, 29 (1971).
2. V. F. Gremenok, G. A. Il’chuk, S. E. Nikitin, V. Yu. Rud’, and Yu. V. Rud’, Fiz. Tekh. Poluprovodn. 39, 218 (2005) [Semiconductors 39, 202 (2005)].
3. V. V. Emtsev, Yu. A. Nikolaev, D. S. Poloskin, V. Yu. Rud’, Yu. V. Rud’, E. I. Terukov, and M. V. Yakushev, Fiz. Tekh. Poluprovodn. 39, 1455 (2005) [Semiconductors 39, 1406 (2005)].
4. V. L. Vinetskii and L. S. Smirnov, Fiz. Tekh. Poluprovodn. 5, 176 (1971) [Sov. Phys. Semicond. 5, 153 (1971)].
5. N. V. Agrinskaya and T. V. Mashovets, Fiz. Tekh. Poluprovodn. 28, 1505 (1994) [Semiconductors 28, 843 (1994)].