1. D. J. Ingram, Electron Spin Resonance and Free Radicals [Russian translation], IL, Moscow (1961).
2. A. D. McLachlan, J. Chem. Phys.32, 1488 (1960).
3. B. I. Shapiro, V. M. Kazakova, and Ya. K. Syrkin, Zh. Struct. Khim.6, 540 (1965).
4. V. M. Kazakova, B. I. Shapiro, I. G. Makarov, and Ya. K. Syrkin, Dokl. Akad. Nauk SSSR,165, 1340 (1965).
5. P. B. Sogo, M. Nakazaki, and M. Calvin, J. Chem. Phys.,26, 1343 (1957).