1. B.Pullman, A.Pullman, Quantum Biochemistry, Interscience Publishers (1963), see pp. 304 & 305.
2. J.M. André, Etude Théorique de la Structure de Bandes des Systèmes Périodiques, Ph.D. Thesis, University of Louvain (UCL), Belgium, (1968) see p. 131 et sq.
3. J.M.André, in Electronic Structure of Polymers and Molecular Crystals, J.M.André, J. Ladik (Eds.), 1, Plenum Press (1975).
4. J.M.André, J. Delhalle, in Quantum Theory of Polymers, J.M.André, J. Delhalle, J. Ladik (Eds.), 1, D.Reidel Publishing Company (1978).
5. J.M.André, Advan. Quantum Chem. 12, 65 (1980).