1. Davydov, A. S., Theory of Molecular Excitons, translated by Kasha, M., and Oppenheimer, jun., M., 1 (McGraw-Hill Book Co., Inc., New York, 1962).
2. Kronick, P. L., Scott, H., and Labes, M. M., J. Chem. Phys. (in the press).
3. Eley, D. D., and Willis, M. R., J. Chem. Soc., 1534 (1963).