1. Topics Appl. Phys., Vol.4;D Menzel,1975
2. Springer Ser. Chem. Phys., Vol.20;D Menzel,1982
3. Springer Chem. Phys., Vol.29,1983
4. T.J. Chuang: Surf. Sci. Rep. 3, 1, 1983
5. P. Piercy, Z.W. Gortel, H.J. Kreuzer. In Advances in Multi-photon Processes and Spectroscopy, Vol.3, ed. by S.H. Lin (World Scientific, Singapore 1987)