1. Michaelis, L., Boeker, G. F., and Reber, R. K., J. Amer. Chem. Soc., 60, 202 (1938).
2. Bleaney, B., and Stevens, K. W. H., “Reports on Progress in Physics”, 16, 109 (1953).
3. Holden, A. N., Kittel, C., Merritt, F. R., and Yager, W. A., Phys. Rev., 77, 147 (1950).
4. See, for example, Wheland, G. W., “Advanced Organic Chemistry”, 54 (Wiley, New York, 1949).
5. Schoenberg, A., Mustafa, A., and Asker, W., J. Amer. Chem. Soc., 73, 2876 (1951).