1. H. Meier, Organic Semiconductors (Verlag Chemie, Weinheim, 1974)
2. M. Pope, C.E. Swenberg, Electronic Processes in Organic Crystals (Clarendon Press, Oxford, 1982)
3. D. Bimberg, I. Eisele, W. Fuchs, H. Kahlert, N. Karl, Landort-Börnstein Numerical Data and Functional Relationships in Science and Technology, New Series Group III 17a-i (1985)
4. W. Warta, N. Karl, Phys. Rev. B 32, 1172 (1985)
5. Y. Maruyama, Mol. Cryst. Liq. Cryst. 171, 287 (1989)