1. H.K. Onnes, Comm.Phys.Lab., Univ. Leyden, Nos. 119,120,122 (1911).
2. J.G. Bednorz and K.A. Müller, Z.Phys. B64, 189 (1986).
3. M.K. Wu, J.R. Asburn, C.J. Torng and P.H. Hor, R.L. Meng, L. Gao, Z.J. Huang, and C.W. Chu, Phys.Rev.Lett. 58, 908 (1987).
4. J.M. Pierce, H.A. Schwettman, W.M. Fairbank, P.B. Wilson, Proc. of the 9th Int.Conf. on Low Temperature Physics, Part A (Plenum Press, N.Y. (1965), p.36.
5. C.M. Lyneis, M.S. McAshan, R.E. Rand, H.A. Schwettman, T.I. Smith and J.P. Turneaure, IEEE Trans.Nucl.Sci., NS-26, 3445 (1981).