1. Werth, G.: Comments At. Mol. Phys.28, 4 (1993)
2. Arbes, F., Benzing, M., Gudjons, Th., Kurth, F., Werth, G.: Z. Phys. D29, 159?161 (1994)
3. Nato ASI Series B: Physics;G. Werth,1990
4. Silverans, R.E., Vermeeren, L., Neugart, R., Lievens, P., ISOLDE Collaboration: Z. Phys. D18, 351 (1991)
5. Goble, A.T., Malecki, S.: Phys. Rev. A42, 1 (1990)