1. E. G. Berzing, Yu. V. Naboikin, I. A. Rom-Krichevskaya, and Yu. A. Tiupov, Opt. i Spektrosk.,22, No. 4, 503 (1967).
2. Yu. M. Gryasnov and A. A. Chastov, Zh. Prikl. Spektrosk.,16, No. 4, 658 (1972).
3. G. V. Venkin, V. O. Zubov, and M. G. Kuz'min, Nonlinear Optics, in: Proceedings of the Second All-Union Symposium on Nonlinear Optics [in Russian], Nauka, Novosibirsk (1968), p. 346.
4. A. M. Ratner and V. S. Chernov, Zh. Tech. Fiz.,39, No. 5, 885 (1969).
5. E. G. Berzing, Yu. V. Naboikin, I. A. Rom-Krichevskaya, and Yu. A.Tiunov, in: Proceedings of the Khar'kov Physicotechnical Institute, Academy of Sciences of the Ukrainian SSR [in Russian] (1970), p. 3.