1. A good description of the breakdown of the one-electron picture in PES has been given in G. Wendin: Structure and Bonding 45 ( Springer, Berlin, Heidelberg 1981 )
2. K. Siegbahn, C. Nordling, R. Fahlman, R. Nordberg, K. Hamrin, J. Hedman, G. Johansson, T. Bergmark, S.-E. Karlsson, I. Lindgren, B. Lindberg: In Nova Acta Regiae Sci. Soc., Upsaliensis, Ser IV, 20 (1967) K. Siegbahn, C. Nordling, G. Johansson, J. Hedman, P.F. Heden, K. Hamrin, U. Gelius, T. Bergmark, L.O. Werme, R. Manne, Y. Baer: ESCA-Applied to Free Molecules ( North-Holland, Amsterdam 1969 )
3. W.C. Price: In Electron Spectroscopy: Theory, Techniques and Applications I, ed. by C.R. Brundle, A.D. Baker ( Academic, New York 1977 )
4. W.L. Jolly: In Electron Spectroscopy: Theory, Techniques and Applications I, ed. by C.R. Brundle, A.D. Baker ( Academic, New York 1977 )
5. H.W.B. Skinner: Proc. Roy. Soc. (London) A135, 84 (1932)