1. G. Blatter, M. V. Feigelman, V. B. Geshkenbein, et al., Rev. Mod. Phys. 66, 1125 (1994).
2. K. V. Baginskii, V. A. Berezin, and V. A. Tulin, Pis’ma Zh. Éksp. Teor. Fiz. 60, 60 (1994) [JETP Lett. 60, 61 (1994)].
3. H. Enríquez, N. Bontemps, P. Fournier, et al., Phys. Rev. B 53, R14 757 (1996).
4. V. A. Berezin and V. A. Tulin, Zh. Éksp. Teor. Fiz. 110, 1054 (1996).
5. L. N. Bulaevskii, M. Ledvij, and V. G. Kogan, Phys. Rev. B 46, 366 (1992).