1. Davydov, A. S.: Theory of Molecular Excitons, Mc Graw-Hill, New York, 1962.
2. Davydov, A. S.: Theory of Molecular Excitons, Plenum Press, New York, 1971. This reference is different in view-point from ref. 1.
3. Craig, D. P. and Walmsley, S. H.: Excitons in Molecular Crystals, Benjamin, New York, 1968.
4. Rice, S.A. and Jortner, J.: in Physics and Chemistry of the Organic Solid State (D. Fox, M. Labes, and A. Weissberger, eds.), Wiley-Interscience, New York, 1967, Vol. III, p. 199.
5. Robinson, G. W.: Ann. Rev. Phys. Chem. 21, 429 (1970).