1. A survey of the literature from 1959 to March 1967 was compiled by W. S. Goree and E. A. Edelsack and issued as a cooperative effort of Stanford Research Institute and the Office of Naval Research. This survey has been continued through a joint publication of the National Bureau of Standards and the Office of Naval Research issued quarterly. It is entitled “Superconducting Devices and Materials” and is currently being compiled by W. S. Goree, E. E. Takken, R. A. Kamper and Neil A. Olien. Copies can be obtained from Cryogenic Data Center, National Bureau of Standards, Boulder, Colorado 80302.
2. F. London, Superfluids, Vol. I (Dover Publications Inc., New York, 1961) p. 82.
3. J. Bardeen, Phys. Rev. Letters 7, l62 (1961)
4. J. E. Mercereau and L. T. Crane, Phys. Letters 7, 25 (1963).
5. W. L. Goodman, W. D. Willis, D. A. Vincent and B. S. Deaver, Jr. Phys. Rev. B (to be published).