1. see e.g. H. Kleinpoppen, Advances in Atomic and Molecular Physics, Academic Press, NY, 423 (1979); M. S. Lubell, Atomic Physics 5 325 (1977); B. Bederson, Atomic Physics 3 401 (1973)
2. B. Bederson, Comments in Atomic and Molecular Physics, 1, 41, 65 (1969); 2, 160 (1971).
3. 1. K. Blum and H. Kleinpoppen, Phys. Rep. 52, 204 (1979)
4. 2. H. Kleinpoppen, Phys. Rev. A _3, 2015 (1971).
5. V. I. Ochkur; zh.Tksp.Teor.Fiz. 45, 734 (1963) (Soviet Physics JETP 18, 503 (1964).