1. Yu. I. Dymshits, V. A. Korobitsyn, and V. G. Neverov, Prib. Tekh. Eksp., No. 1, 274?275 (1977).
2. N. A. Koehler, L. J. Ferderber, D. L. Readhead, and P. J. Ebert, Phys. Rev. A,12, No. 3, 968?973 (1975).
3. I. M. Belousova, Yu. N. Dymshits, A. G. Kavetskii, et al., Opt. Spektrosk.,44, No. 6, 952?956 (1978).
4. I. V. Kosinskaya and L. T. Polozova, Opt. Spektrosk.,30, No. 5, 853?858 (1971).
5. D. Emmons, Opt. Commun.,11, No. 3, 257?260 (1974).