1. E. W. Collings, F. J. Jelinek, J. C. Ho, and M. P. Mathur, in Advances in Cryogenic Engineering, Vol. 22, Plenum Press, New York (1977), p. 159.
2. G. G. Lessman, W. A. Logsdon, R. Kossowsky, M. P. Mathur, and J. M. Wells, in Materials Research for Superconducting Machinery, Vol. I, NBS/ARPA Semi-Annual Technical Report, AD780596 (1974), p. 59
3. J. E. Campbell, E. A. Eldridge, and J. K. Thompson, in Materials Research for Superconducting Machinery, Vol. I, NBS/ARPA Semi-Annual Technical Report, AD780596 (1974)
4. F. Heiniger, E. Bucher, and J. Muller, Phys. kondens Materie
5:243 (1966).
5. P. Zoller, P. R. Decker, and J. R. Dillinger, J. Appl. Phys.
40:1964 (1969).