1. V. A. Kiselev, B. V. Novikov, and A. E. Cherednichenko, Exciton Spectroscopy of the Near-Surface Region of Semiconductors [in Russian], LGU, Leningrad (1987), p. 162.
2. A. S. Batyrev, N. V. Karasenko, and B. V. Novikov, Vestn. St. Petersb. Univ. 4(1(4)), 28 (1994).
3. J. A. Bragagnolo, G. M. Storti, and K. W. Boer, Phys. Status Solidi A 22, 639 (1974).
4. R. A. Bisengaliev, E. D. Batyrev, B. V. Novikov, and A. V. Sel’kin, in Abstracts of the International Conference “Optics of Excitons in Condensed Matter,” St. Petersburg (1997), p. 68.
5. R. W. Smith, Phys. Rev. 105, 900 (1957).