1. J.G. Bednorz and K.A. Müller, Z. Phys. B64,189 (1986)
2. For example: P. B. Allen, Comments on Condensed Matter Physics, part B XV, 327(1992)
3. B. Batlogg, in “High Temperature Superconductivity”, Los Alamos Symposium, Addison-Wesley Pub., 1990, p.37; Physics Today, June 1991, 44; Physica B 169, 7 (1991)
4. P. Fulde and P. Horsch, Europhysics News 24, 73 (1993)
5. V. J. Emery, Physica B 169, 17(1991)