1. An extensive treatment of the properties of a solid state electron gas is contained in “The Theory of Fermi Liquids” D. Pines and P. Nozieres, W. A. Benjamin Co. Inc., New York, 1966;
2. and “Elementary Excitations in Solids”, D. Pines, W. A. Benjamin Co. Inc., New York, 1963.
3. P.M. Platzman, Phys. Rev. 139, A379 (1965).
4. A.L. McWhorter, “Physics of Quantum Electronics,” p. 111, P. L. Kelley, B. Lax, and P.E. Tannenwald (eds.) McGraw-Hill Book Company Inc., New York, 1966.
5. P.A. Wolff, Phys. Rev. Letters 16, 225 (1966).