1. see the special issues entitled: “Aromaticity” in Chem. Rev. 2001, 101; “Delocalization- pi and sigma” in Chem. Rev. 2005, 105 and “Challenges in aromaticity: 150 years after Kekulé’s benzene”;Chem. Soc. Rev.,2015
2. Introduction: aromaticity;Schleyer;Chem. Rev.,2001
3. On new compounds of carbon and hydrogen, and on certain other products obtained during the decomposition of oil by heat;Faraday;Phil. Trans. R. Soc. London,1825
4. On insolinic acid;Hofmann;Proc. R. Soc.,1857
5. Sur la constitution des substances aromatiques;Kekulé;Bull. Soc. Chim. Paris,1865