1. L. P. Rice, L. P. Campbell and W. F. Simons, in: Advances in Cryogenic Engineering, Vol 8, Plenum Press, New York (1963), p. 671.
2. J. G. Kaufman, K. O. Bogardus, and E. T. Wanderer, in: Advances in Cryogenic Engineering, Vol. 13, Plenum Press, New York (1968), p. 294.
3. ASTM Standard (Part 30) (1966), p. 136.
4. C. J. Guntner and R. P. Reed, in: Advances in Cryogenic Engineering, Vol. 6, Plenum Press, New York (1961), p. 565.
5. J. S. DeSisto and L. C. Carr, in: Advances in Cryogenic Engineering, Vol. 6, Plenum Press, New York (1961), p. 577.