1. O. A. Anikeenok, Available from VINITI, No. 2442-B87 (1987).
2. O. A. Anikeenok, Fiz. Tverd. Tela (St. Petersburg) 45(5), 812 (2003) [Phys. Solid State 45 (5), 854 (2003)].
3. O. A. Anikeenok, Fiz. Tverd. Tela (St. Petersburg) 47(6), 1065 (2005) [Phys. Solid State 47 (6), 1100 (2005)].
4. M. V. Eremin and A. M. Leushin, Fiz. Tverd. Tela (Leningrad) 16(7), 1917 (1974) [Sov. Phys. Solid State 16 (7), 1252 (1974)].
5. M. V. Eremin and A. A. Kornienko, Fiz. Tverd. Tela (Leningrad) 19(10), 3024 (1977) [Sov. Phys. Solid State 19 (10), 1769 (1977)].