1. R. W. Whitworth,Proc. Roy. Soc. Lond. 246A, 390 (1958); S. Greywall,Phys. Rev. 23B, 2152 (1981).
2. T. Satoh, T. Satoh, T. Ohtsuka, and M. Okuyama,Physica 145B, 379 (1987); M. Okuyama, T. Satoh, and T. Satoh,Physica 154B, 116 (1988).
3. L. D. Landau and E. M. Khalatnikov;Zh. Eksp. Teor. Fiz. 19, 637, 709 (1949);Collected Papers of L. D. Landau D. Ter Haar, ed. (Pergamon, Oxford, 1965), p. 494. See also K. R. Atkins,Liquid Helium (Cambridge University Press, London, 1959), J. Wilks,Liquid and Solid Helium (Clarendon, Oxford, 1967).
4. J. C. WheatleyProgress in Low Temperature Physics, Vol. VI, C. J. Gorter, ed. (North-Holland, Amsterdam, 1970), p. 133.
5. J. T. Tough, W. D. McCormick and J. G. Dash;Rev. Sci., Instrum. 1345 (1964);