1. Bazylev, V. A., Chibisov, M. I. (1981): Soy. Phys. Usp. 24, 276.
2. Bell, K. L., Gilbody, H. B., Hughes, J. G., Kingston, A. E., Smith, F. J. (1983): J. Phys. Chem. Ref. Data 12, 891; also see report: Cullham Laboratory Report CLM-R216 (1982).
3. Burgess, A., Summers, H. P., Cochrane, D. M., McWhirter, R. W. P. (1977): Monthly Notices Roy. Astron. Soc. 179, 275.
4. Crandall, D. H. (1981): Physica Scr. 23, 153.
5. Crandall, D. H. (1982): Physics of Electronic and Atomic Collisions (Datz, S., ed.), 595. Amsterdam: North-Holland.