1. A. F. Andreev, Sov. Phys. JETP19, 1228 (1964).
2. M. Nahum and J. M. Martinis, submitted to Appl. Phys. Lett.
3. See for instance: L. Solymar, Superconductive Tunnelling and Applications, (Wiley, New York, 1972).
4. R. P. Welty and J. M. Martinis, IEEE Trans. Appl. Superconductiity3, 2605 (1993).
5. See for instance: F. C. Wellstood, Ph.D. thesis, University of California at Berkeley (Univ. Microfilms Int., Ann Arbor, MI.) 1985, and references therein.