1. Bardeen, J., Cooper, L.N. and Schrieffer, J.R., Phys. Rev., 106, 1957, 162; 108, 1957, 1175
2. For discussion of the Eliashberg equations [originally formulated by G.M. Eliashberg, Sov. Phys. JETP, 11, 1960, 696] we refer to P.B. Allen and B. Mitrović, Solid State Physics: Advances in Research and Applications, Vol. 37, p. 1. Academic, New York, 1982
3. Transition Temperature of Strong-Coupled Superconductors
4. Kresin, V.Z., Gutfreund, H. and Little, W.A., Solid State Commun., 51, 1984, 339; Kresin, V.Z., Phys. Lett., A122, 1987, 434
5. Davis, P.J. in Handbook of Mathematical Functions (Edited by M. Abramowitz and I.A. Stegun), p. 253. Dover, New York, 1965