1. Wuilleumier, F.J. (ed.): Photoionization and other probes of many-electron interactions New York: Plenum 1976
2. Heinzmann, U.: Appl. Opt.19, 4087 (1978)
3. Siegel, A., Ganz, J., Bussert, W., Hotop, H.: J. Phys. B (to be published)
4. Lin, S.H.: Can. J. Phys.46, 2719 (1968)
5. Klar, H., Kleinpoppen, H.: J. Phys. B15, 1933 (1982)