1. H. Tawara and A. Russek, Rev. Mod. Phys. 45, 178 (1973).
2. R. A. Mapleton, The Theory of Charge Exchange, (Wiley-Interscience, New York, 1972).
3. D. H. Madison and E. Merzbacher in Atomic Innter Shell Processes, ed. B. Crasemann, p. 1 (Academic Press, New York, 1975).
4. J. R. Macdonald, C. L. Cocke and W. Edson, Phys. Rev. Lett. 32, 648 (1974).
5. J. R. Macdonald, L. M. Winters, M. D. Brown, L. D. Ellsworth, T. Chiao and E. Pettus, Phys. Rev. Lett. 30, 251 (1973); and Phys. Rev. A8, 1835 (1973).