1. J. G. Bednorz and K. A. Müller,Z. Phys. B 64, 189 (1986); M. K. Wu, J. R. Ashburn, C. J. Torng, P. H. Hor, R. L. Meng, L. Gao, Z. J. Huang, Y. Q. Wang, and C. W. Chu,Phys. Rev. Lett. 58, 908 (1987).
2. A. A. Abrikosov,Zh. Eksp. Theor. Fiz. 32, 1442 (1957);Sov. Phys. JETP 5, 1174 (1957).
3. M. Tinkham,Introduction to Superconductivity (McGraw Hill, New York, 1975); P. G. De Gennes,Superconductivity of Metals and Alloys (Benjamin, New York, 1966); A. A. Abrikosov,Fundamentals of the Theory of Metals (North Holland, Amsterdam, 1988).
4. U. Essmann and H. Träuble,Phys. Lett. A 24, 526 (1967);Sci. Am. 224, 75 (March 1971).
5. E. H. Brandt and U. Essmann,Phys. Status Solidi (B) 144, 13 (1987) (review).