1. Landau, L.D.: Soviet. Phys. JETP3, 920 (1957)
2. Landau, L.D.: Soviet. Phys. JETP5, 101 (1957)
3. Wheatley, J.C.: Prog. Low. Temp. Phys. Vol VI, p. 77, Amsterdam: North-Holland 1970
4. Platzman, P.M., Wolff, P.A.: Solid State Phys., Suppl. 13, New York: Academic Press 1973
5. Migdal, A.B.: Nuclear Theory: The Quasiparticle Method, New York: Benjamin 1968