1. Extensive bibliographies for the two-level problem are contained in L. Allen and J.H. Eberly, Optical Resonance and Two-Level Atoms (Wiley, New York, 1975 ), and M. Sargent III, M.O. Scully, and W.E. Lamb, Jr., Laser Physics, (Addison-Wesley, Reading, Mass. 1974 ).
2. N. Rosen and C. Zener, Phys. Rev. A 40, 502 (1932)
3. R.T. Robiscoe, Phys. Rev. A 17, 247 (1978).
4. R.T. Robiscoe, Phys. Rev. A 27, 1365 (1983).
5. A.E. Kaplan, Sov. Phys. JETP 41, 409 (1976).