1. G. LeLay, J. Vac. Sci. Technol. B2, 354 (1983).
2. C. Calandra, O. Bisi and G. Ottaviani, Surf. Sci. Rep. 4, 271 (1984).
3. L. Brillson, Handbook of Synchrotron Radiation, Vol.11, ed. G.V. Marr (Amsterdam: North-Holland, 1985).
4. T. Kendelewicz and I. Lindau, Crit. Rev. 13, 27 (1986).
5. G. Margaritondo, Solid State Electron. 29, 123 (1983).