1. Mattis, D. C., andJ. Bardeen: Phys. Rev.111, 412 (1958).
2. Gor'kov, L. P.: J. Exptl. Theoret. Phys. (U.S.S.R.)37, 1407 (1959); (Soviet Phys.-JETP10, 998 (1960)).
3. Abrikosov, A. A., andL. P. Gor'kov: J. Exptl. Theoret. Phys. (U.S.S.R.)39, 1781 (1960); (Soviet Phys.-JETP12, 1243 (1961)).
4. Anderson, P. W.: J. Phys. Chem. Solids11, 26 (1959).
5. — Proceedings of the Toronto Conference on Low Temperature Physics, p. 298.