1. See, for example, G. S. Agarwal and N. Nayak, J. Opt. Soc. Amer. B 1 (1984) 164; H. Friedman and A. P. Wilson-Gordon, Phys. Rev. A 36 (1987) 1333; N. B. Manson, C. Wei, and J. P. D. Martin, Phys. Rev. Lett. 76 (1996) 3943; H. S. Freedhoff and Z. Ficek, Phys. Rev. A 58 (1998) 1296.
2. B. R. Mollow, Phys. Rev. A 5 (1972) 2217.
3. Haroche and Hartmann [S. Haroche and F. Hartmann, Phys. Rev. A 6 (1972) 1280] obtained the probe absorption spectrum in the context of velocity-tuned resonances in the theory of saturated absorption. They interpreted the structure centered near 5 = 0 as a competition between the two processes shown in Fig. 3 (a),(b) (which cancel exactly in our model). In the context of the relaxation model used in their paper, their amplitude interpretation does not appear to be justified.
4. F. Y. Wu, S. Ezekiel, M. Ducloy, and B. R. Mollow, Phys. Rev. Lett. 38 1077 (1977).
5. C. Cohen-Tannoudji and S. Reynaud, J. Phys. B 10 (1977) 345.