1. M. P. Chaika, Interference of Degenerate Atomic States [in Russian], Leningrad Univ. Press, Leningrad (1975); E. B. Aleksandrov, G. I. Khvostenko, and M. P. Chaika, Interference of Atomic States, Springer-Verlag, New York (1993).
2. P. A. Apanasevich, Basics of the Interaction of Light with Matter [in Russian], Nauka i Tekhnika, Minsk (1977).
3. S. G. Rautian, G. I. Smirnov, and A. M. Shalagin, Nonlinear Resonances in the Spectra of Atoms and Molecules [in Russian], Nauka, Novosibirsk (1979); S. G. Rautian and A. M. Shalagin, Kinetic Problems of Nonlinear Spectroscopy, North-Holland, Amsterdam (1991).
4. A. K. Popov, Introduction to Nonlinear Spectroscopy [in Russian], Novosibirsk, Nauka (1983).
5. A. Javan, Phys. Rev. 107, 1579 (1957); V. M. Kontorovich and A. M. Prokhorov, Zh. Éksp. Teor. Fiz. 33, 1428 (1957) [Sov. Phys. JETP 6, 1100 (1958)]; T. Yajima and K. Shimoda, J. Phys. Soc. Jpn. 15, 1668 (1960); Adv. Quantum Electron. 3, 548 (1961); V. M. Fain and Ya. I. Khanin, Quantum Radiophysics, Vol. 1: V. M. Fain, Photons and Nonlinear Media [in Russian], Sovetskoe Radio, Moscow (1972), p. 389 [English translation: Quantum Electronics, 2 vols., Pergamon Press, Oxford (1969)].