1. N. Trinajstic, inSemiempirical Methods of Electronic Structure Calculations, Part A: Techniques, G. A. Segal (ed.), Plenum Press, New York (1977).
2. E. HeilbronnerHelv. Chim. Acta,36, 170–188 (1953).
3. E. Heilbronner,——ibid.37, 913–921 (1954).
4. E. Streitweiser,Molecular Orbital Theory for Organic Chemists, Wiley, New York (1962).
5. K. Balasubramanian, inChemical Applications of Topology and Graph Theory, R. B. King (ed.), Elsevier, Amsterdam (1983).