1. 1) E. Hückel, Z. Physik, 70, 204 (1931)
2. 2) V. I. Minkin, M. N. Glukhovtsev, B. I. A. Simkin, Aromaticity and antiaromaticity: electronic and structural aspects, J. Wiley & Sons, 1994
3. 3) P. J. Garratt, Aromaticity, John Wiley & Sons Ltd., New York, 1986
4. 4) E. V. Anslyn, D. A. Dougherty, Modern Physical Organic Chemistry, University Science Books, 2005
5. 5) R. Gleiter, G. Haberhauer, R. Hoffmann, Aromaticity and Other Conjugation Effects, Wiley-VCH, 2012