1. Stern, E.A., Heald, S.M.: In: Handbook on synchrotron radiation. Koch, E.-E. (ed.), Vol. 1B, Chap. 10, pp. 995?1014. New York: North Holland 1983
2. Doniach, S., Sunjic, M.: J. Phys. C3, 285 (1970)
3. For example the anomolous X-ray photoelectron spectrum of Xe; Siegbahn, K., Nordling, C., Johansson, G., Hedman, J., Hedin, P.F., Hamrin, K., Gelius, U., Bergmark, T., Werme, L.O., Manne, R., Baer, Y.: ESCA applied to free molecules. Amsterdam: North Holland 1969
4. See for example: H�fner, S., Werthiem, G.K.: Phys. Lett. A51, 299 (1975); Wendin, G.: Phys. Rev. Lett.53, 724 (1984); Takeo, Jo, Sawatzky, G.A.: Phys. Rev. B43, 8771 (1991); Chen, C.T., Smith, N.V., Sette, F.: Phys. Rev. B43, 6785 (1991)
5. LaGraffe, D., Dowben, P.A., Dottl, L., Ufuktepe, Y., Onellion, M.: Z. Phys. B ? Condensed Matter82, 47 (1991)