1. Abignoli, M., Barat, M., Baudon, J., Fayeton, J., Houver, J. C., 1972, J. Phys. 5: 1533.
2. Allan, R. J., Bähring, A., Haussen, J., 1985, to be published.
3. Andersen, N., 1980, Physikalische Blatter 36: 219.
4. Andersen, N., Andersen, T., Ostgaard Olsen., J., Horsdal Pedersen, E,, 1980, J. Phys. 6 13: 2421.
5. Aydinol, M., Hippler, R., McGregor, I., Kleinpoppen, H., 1980, J. Phys. B 13:989; 1981, in “Coherence and Correlation in Atomic Collisions”, H. Kleinpoppen and J. F. Williams, eds., Plenum Press, New York, p. 205.