1. J. W. Dean, J. A. Brennan, and D. B. Mann, in: Advances in Cryogenic Engineering, Vol. 14, Springer Science+Business Media New York (1969), p. 299.
2. T. R. Strobridge, NBS Tech. Note 129 (January 1962).
3. J. W. Dean, J. A. Brennan, D. B. Mann, and C. H. Kneebone, NBS Tech. Note 606 (July 1971).
4. J. A. Brennan, J. W. Dean, D. B. Mann, and C. H. Kneebone, NBS Tech. Note 605 (July 1971).