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2. J. A. Derrington, R. Clare, D. E. Wood, and C. Norton, in: Proceedings of the XIIth International Congress of Refrigeration, Vol. 1, International Institute of Refrigeration (1969), p. 195.
3. R. H. Kropschot, in: Applied Cryogenic Engineering (R. W. Vance, ed.), John Wiley and Sons, New York (1962), chapt. 6.
4. R. H. Kropschot, Cryogenic Technology (R. W. Vance, ed.), John Wiley and Sons, New York (1963), chapt. 7.
5. R. F. Barron, Cryogenic Systems, McGraw-Hill, New York (1966).