1. M. Henzler: Surf. Sci.73, 240 (1978);
2. M. Henzler: InElectron Spectroscopy for Surface Analysis, ed. by H. Ibach, Topics Curr. Phys., Vol.4 (Springer, Berlin, Heidelberg 1977)
3. M.G. Lagally: In Chemistry and Physics of Solid Surfaces IV, ed. by R. Vanselow, R. Howe, Springer Ser. Chem. Phys., Vol.20 (Springer, Berlin, Heidelberg 1982)
4. T.-M. Lu, L.H. Zhao, M.G. Lagally, G.-C. Wang, J.E. Houston: Surf. Sci. 122, 519 (1982)
5. C.S. Lent, P.I. Cohen: Surf. Sci. 139, 121 (1984)