1. M. O. Scully, Phys. Rev. Lett. 55, 2802 (1985).
2. P. E. Toschek and J. Hall, Abstract in XV International Conference on Quantum Electronics, J.O.S.A. B 4, 124 (1987).
3. For a theoretical account on the experiment of reference 2, see: J. Bergou and M. Orszag (to appear in J. O. S. A. B).
4. M. Ohtsu and K. Y. Liou (preprint).
5. M. O. Scully, and K. Wodkiewicz (to be published).