1. V. A. Zalozh, S. A. Moskalenko, and A. Kh. Rotaru, Zh. Éksp. Teor. Fiz. 95, 601 (1989) [Sov. Phys. JETP 68, 338 (1989)].
2. V. A. Zalozh, A. Kh. Rotaru, and V. Z. Tronciu, Zh. Éksp. Teor. Fiz. 103, 994 (1993) [JETP 76, 487 (1993)].
3. V. A. Zalozh, A. Kh. Rotaru, and V. Z. Tronciu, Zh. Éksp. Teor. Fiz. 105, 260 (1994) [JETP 78, 138 (1994)].
4. A. Kh. Rotaru and K. V. Shura, Zh. Éksp. Teor. Fiz. 107, 450 (1995) [JETP 80, 240 (1995)].
5. A. Kh. Rotaru and K. V. Shura, Fiz. Tverd. Tela (Leningrad) 33, 1973 (1991) [Sov. Phys. Solid State 33, 1111 (1991)].