1. also in: Collected Papers edited by L. D. Landau (Pergamon Press New York 1965).
2. See alsoL.D.LandauandE.M.Lifshitz Lehrbuch der Theoretischen Physik IX: Statische Physik Vol. 2 (Akademie‐Verlag Berlin 1984).
3. N.R.Werthammer in: Superconductivity edited by R. D. Parks (Marcel Dekker New York 1969) p. 321.
4. P.G.de Gennes Superconductivity of Metals and Alloys (Benjamin New York 1966).