1. V. N. Bogomolov, D. A. Kurdyukov, A. V. Prokof’ev, et al., Pis’ma Zh. Éksp. Teor. Fiz. 63, 496 (1996) [JETP Lett. 63, 520 (1996)].
2. M. E. Kompan and N. Yu. Shibanov, Fiz. Tekh. Poluprovodn. (St. Petersburg) 29, 1859 (1995) [Semiconductors 29, 971 (1995)].
3. P. A. Ivanov and V. E. Chelnokov, Fiz. Tekh. Poluprovodn. (St. Petersburg) 29, 1921 (1995) [Semiconductors 29, 1003 (1995)].
4. V. A. Karachinov, in Proceedings of the 3rd International Conference “Crystals: Growth, Properties, Real Structure, Application” (VNIISIMS, Aleksandrov, 1997), Vol. 2, p. 240.
5. Yu. V. Deryugin, Single Crystals of Corundum in Jewellery Industry (Mashinostroenie, Leningrad, 1984).