1. E. M. Lifshits and L. P. Pitaevski, Course of Theoretical Physics, Vol. 9: Statistical Physics, Part 2 (Nauka, Moscow, 2000; Pergamon, New York, 1980).
2. P. G. de Gennes, Superconductivity of Metals and Alloys (Bengamin, New York, 1966; Mir, Moscow, 1968).
3. J. Feder, Solid State Commun. 5, 299 (1967).
4. V. I. Marchenko and E. R. Podolyak, J. Exp. Theor. Phys. 97, 154 (2003).
5. W. A. Little and R. D. Parks, Phys. Rev. Lett. 9, 9 (1962).