1. J. A. McLennan, Jr., Adv. Chem. Phys.,5, 261 (1963).
2. L. Kadanoff and P. C. Martin, Ann. Phys.,24, 419 (1963).
3. A. D. Khon'kin, Dokl. Akad. Nauk, SSSR,183, 1285 (1968).
4. L. van Hove, Phys. Rev.,95, 249 (1954).
5. I. Z. Fisher and L. I. Komarov, Zh. Éksp. Teor. Fiz.,43, 1927 (1962).