1. P. J. Garratt , Aromaticity, Wiley, New York, 3rd edn, 1986
2. V. I. Minkin , M. N.Glukhovtsev and B. Y.Simkin, Aromaticity and Antiaromaticity: Electronic and Structural Aspects, Wiley, New York, 1994
3. for recent reviews about aromaticity see the special issue entitled: Aromaticity, ed. Virgil Percec, Chem. Rev., 2001, 101
4. Delocalization—pi and sigma, ed. J. A. Gladysz, Chem. Rev., 2005, 105