1. G. K. White, Proceedings of the Eighth International Conference on Low Temperature Physics, Butterworths, London (1963), p. 394.
2. E. A. Lynton, Superconductivity, Methuen & Co. London (1962), p. 80.
3. L. J. Barnes and J. R. Dillinger, Phvs. Rev. Letters, 10:287 (1963).
4. R. L. Powell and W. A. Bianpied, NBS Circular 556 (1954).
5. R. C. Johnson and W. A. Little, Phys. Rev., 130:596 (1963).