1. A. V. Bogdanov and Yu. E. Gorbachev, Izv. Vyssh. Uchebn. Zaved., Fiz., No. 8, 27 (1978).
2. A. V. Bogdanov and Yu. E. Gorbachev, Izv. Vyssh. Uchebn. Zaved., Fiz., No. 8, 32 (1978).
3. J. Seiden, C. R. Acad. Sci., B276, 905 (1973).
4. The Helium Liquids, Academic Press, New York (1975).
5. A. V. Bogdanov and G. V. Dubrovskii, Teor. Mat. Fiz.,28, 80 (1976).