1. Comprehensive Organic Chemistry, The Synthesis and Reactions of Organic Compounds, vol. 4;Staunton,1979
2. The Chemistry of Heterocyclic Compounds, Chromenes, Chromanones and Chromones, vol. 31;Ellis,1977
3. Comprehensive Heterocyclic Chemistry II, A Review of the Literature 1982–1995, vol. 5;Hepworth,1996
4. Comprehensive Heterocyclic Chemistry, The Structure, Reactions, Synthesis and Uses of Heterocyclic Compounds, vol. 3;Brogden,1984
5. J. March, in: Advanced Organic Chemistry, Reactions, Mechanisms, and Structure, Wiley, New York, 1992, p. 51 see also pages 335, 741.