1. “Angle-resolved Photoemission” (S.D. Kevan, editor), Vol. 74 of “Studies in Surface Science and Catalysis”, Elsevier, Amsterdam, 1992, and many references therein 111
2. N.V. Smith, Phys. Rev. B32 (1985) 3549
3. S.G. Davison and M. Steslicka, “Basic Theory of Surface States”, ClarendonPress, Oxford 1992
4. F. Forstmann, Progr. Surface Sci. 42 (1993) 21
5. N. V. Smith, Appl. Surface Sci. 22/23 (1985) 349