1. See e.g. C.Kittel, Quantum Theory of Solids [J.Wiley, New-York (1963)].
2. T. Kihara, O. Aono, T. Dodo, Nuclear Fusion 2, 66 (1962).
3. A. I. Alekseev, Yu. P. Nikitin, Soviet Phys. J.E.T.P. 23, 608 (1966).
4. E.G. Harris, Adv. Plasma Phys. 3, 157 (1969).
5. N. P. Landsman, CH. G. van Weert, Phys. Reports 145, 141 (1987).