1. “Chemistry of the Alkaloids”;Pelletier,1970
2. “Alkaloids: Chemical and Biological Perspectives”;Pelletier,1984
3. “Ciba Foundation Symposium on the Chemistry and Biology of Purines.”;Wolstenholme,1957
4. Physicochemical Aspects of the Chemistry of Purines
5. R.K. Robins. Heterocycl. Compd. (1967).