1. V. I. Vinogradov and A. V. Eletskii, Opt. Spektrosk. 30(5), 830 (1971).
2. V. I. Vinogradov and A. V. Eletskii, Opt. Spektrosk. 30(5), 850 (1974).
3. V. I. Vinogradov, Opt. Spektrosk. 107(2), 337 (2009) [Opt. Spectrosc. 107 (2), 310 (2009)].
4. V. I. Vinogradov, Opt. Spektrosk. 110(6), 1038 (2011) [Opt. Spectrosc. 110 (6), 982 (2011)].
5. V. S. Letokhov and V. P. Chebotaev, Principles of Nonlinear Laser Spectroscopy (Nauka, Moscow, 1985) [in Russian].