1. P. J. Feibelman, Prog. Sufr. Sci. 12, 287 (1982).
2. A. Williams and U. Barth, in Theory of the Inhomogeneous Electron Gas, Ed. by S. Lundqvist and N. H. March (Plenum, New York, 1983; Mir, Moscow, 1987).
3. D. J. W. Gerdart, M. Rasolt, and R. Taylor, Solid State Commun. 10, 279 (1972).
4. V. V. Nemoshkalenko and V. N. Antonov, in Methods of Computational Physics in the Theory of Solids: The Band Theory of Metals (Naukova Dumka, Kiev, 1985), p. 238.
5. Lect. Notes Phys.;H. Ebert,2000