1. J. Wilks: Liquid and Solid Helium (Oxford. London 1967)
2. See, for example, D.P. Woodruff: The Solid-Liquid Interface (Cambridge Univ, Press, London 1973)
3. A.F. Andreev, A.Y. Parshin: Sov. Phys. JETP 48, 763 (1979)
4. A.F. Andreev, V.G. Knizhnik: Sov. Phys. JETP 56, 226 (1982)
5. R.M. Bowley, D.O. Edwards: J. Phys. 44, 723 (1983)