1. R. Berkovits and M. Kaveh, Phys. Rev. B: Condens. Matter 37, 584 (1988).
2. R. Berkovits, D. Eliyahu, and M. Kaveh, Phys. Rev. B: Condens. Matter 41, 407 (1990).
3. E. E. Gorodnichev, S. L. Dudarev, and D. B. Rogozkin, Zh. Éksp. Teor. Fiz. 96(3), 847 (1989) [Sov. Phys. JETP 69 (3), 481 (1989)].
4. V. V. Rumyantsev, Soros. Obraz. Zh. 5(2), 98 (1999).
5. B. N. Libenson, K. Yu. Platonov, and V. V. Rumyantsev, Zh. Éksp. Teor. Fiz. 101(2), 614 (1992) [Sov. Phys. JETP 74 (2), 326 (1992)].