1. D. Bimberg, H. Munzel, A. Steckenborn, and J. Christen, Phys. Rev. B 31, 7788 (1985).
2. Ya. Yu. Aaviksoo, I. Ya. Reimand, V. V. Rossin, and V. V. Travnikov, Pis’ma Zh. Éksp. Teor. Fiz. 53(7), 377 (1991) [JETP Lett. 53, 395 (1991)].
3. D. Z. Garbuzov, V. B. Khalfin, M. K. Trukan, et al., Fiz. Tekh. Poluprovodn. (Leningrad) 12, 1368 (1978) [Sov. Phys. Semicond. 12, 809 (1978)].
4. R. Dingle, Phys. Rev. 184, 788 (1969).
5. A. M. Gilinsky and K. S. Zhuravlev, Appl. Phys. Lett. 68, 373 (1996).