1. B. D. Josephson:Phys. Lett.,1, 251 (1962).
2. R. P. Feynman:The Feynman Lectures on Physics (New York, 1963).
3. P. G. De Gennes:Superconductivity o] Metals and Alloys (New York, 1966).
4. D. J. Scalapino: inTunneling Phenomena in Solids, edited byE. Burnstein andS. Lundquist (New York, 1969).
5. M. M. Nieto:Phys. Rev.,167, 416 (1968).