1. M. Davies, The Physical Principles of Gas Liquefaction and Low Temperature Rectification, Longmans Green & Co., London and New York, p. 24.
2. Collins, S. C., and Cannaday, R. L., Expansion Machines for Low Temperature Processes, Oxford University Press, London and New York (1958).
3. Mann, D. B., Bjorklund, W. R., Macinko, J., and Hiza, M. J., Advan. Cryog. Eng.
5, 346 (1959).
4. Scott, R. B., Denton, W. H., and Nicholls, C. M., Technology and Uses of Liquid Hydrogen, Pergamon, London and New York (1964);
5. see also Singleton, A. H., Lapin, A., and Wenzel, L. A., Advan. Cryog. Eng.
13, 409 (1968).