1. C.P. Flyn, A.M. Stoneham, Phys. Rev. B 1, 3966 (1970)
2. A.F. Andreev, I.M. Lifshitz, Zh. Eksp. Teor. Fiz. 56, 2057 (1969)
3. J.A. Sussman, Ann. Phys., Paris 6, 135 (1971)
4. Yu. Kagan, L.A. Maximov, Zh. Eksp. Teor. Fiz. 65, 622 (1973)
5. Yu. Kagan, M.I. Klinger, J. Phys. C 7, 2791 (1973)