1. G. M. Zhidomirov and Yu. D. Tsvetkov, Opt. Spektrosk.,17, 67 (1964).
2. D. Syryanarayana and M. D. Sevilla, J. Chem. Phys.,72, 1325 (1980).
3. S. A. Dzuba, K. M. Salikhov, and Yu. D. Tsvetkov, Chem. Phys. Lett.,79, 568 (1981).
4. K. M. Salikhov, A. G. Semenov, and Yu. D. Tsvetkov, Electron Spin Echo and Its Application [in Russian], Nauka, Novosibirsk (1976).
5. J. A. Pople, W. J. Schneider, and H. J. Bernstein, High-Resolution Nuclear Magnetic Resonance, McGraw-Hill, New York (1959).