1. Greene, F. D., Chu, C.-C., and Walia, J., J. Amer. Chem. Soc., 84, 2463 (1962).
2. McConnell, H. M., and Fessenden, R. W., J. Chem. Phys., 31, 1688 (1959).
3. See, for example, Symons, M. C. R., Adv. Phys. Org. Chem., edit. by Gold, V., 1, 284 (1963).
4. Atkins, P. W., Keen, N., and Symons, M. C. R., J. Chem. Soc., 250 (1963).
5. Fessenden, R. W., Quart. Rep. Mellon Inst., April-June (1961).