1. H. Okuyama, K. Nakano, T. Miyajima, and K. Akimoto, Jpn. J. Appl. Phys. 30, L1620 (1991).
2. Excitons, edited by E. I. Rashba and M. D. Sturge, Modern Problems in Condensed Matter Sciences (North-Holland, Amsterdam, 1982), Vol. 2; Nauka, Moscow, 1985.
3. K. Kheng, R. T. Cox, V. P. Kochereshko, K. Seminadayar, S. Tatarenko, F. Bassani, and A. Franciosi, Superlattices Microstruct. 15, 253 (1994).
4. E. L. Ivchenko, P. S. Kop’ev, V. P. Kochereshko, I. N. Ural’tsev, D. R. Yakovlev, S. V. Ivanov, B. Ya. Mel’tser, and M. A. Kalitievskii, Fiz. Tekh. Poluprovodn. 22, 784 (1988) [Sov. Phys. Semicond. 22, 495 (1988)]; E. L. Ivchenko and G. E. Pikus, Superlattices and Other Heterostructures. Symmetry and Optical Phenomena, Springer Series in Solid-State Sciences (Springer, Berlin, 1995), Vol. 110.
5. J. Puls, V. V. Rossin, F. Henneberger, and R. Zimmermann, Phys. Rev. B 54, 4974 (1996).