1. A.A. Abrikosov: Sov. Phys. JETP 5, 1174 (1957)
2. M. Tinkham: Introduction to Superconductivity (Mc Graw Hill, New York, 1975)
3. P.G. De Gennes: Superconductivity of Metals and Alloys (W.A. Benjamin, New York, 1966)
4. G. Blatter et al.: Rev. Mod. Phys. 66, 1125 (1994)
5. H. Brandt: Rep. Prog. Phys. 58, 1465 (1995)