1. Clementi,E.: Int. J. quant. Chemistry, Symposium 1969, No. 3, Pt. I, p. 179.
2. Quantum Chemistry Program Exchange, Chemistry Department, Indiana University, USA.
3. Palmer,M.H.: The structure and reactions of heterocyclic compounds. London: Edward Arnold 1967.
4. Clementi,E.: J. chem. Physics 46, 4731, 4737 (1967) and later papers.
5. ?: J. chem. Physics 46, 4725 (1967).