1. P.J. Garratt, Aromaticity, Wiley, New York, 1986.
2. D. Lloyd, The Chemistry of Conjugated Cyclic Compounds, Wiley, New York, 1989.
3. V. Minkin, M. Glukhotsev, B. Simkin, Aromaticity and Antiaromaticity, Wiley, New York, 1994.
4. Some comments on the use of the "ring-current" concept in diagnosing and defining "aromaticity"