1. (c) Grethe, G.; Uskoković, M. R. InThe Chemistry of Heterocyclic Compounds; Sexton, J. E., Ed.; Wiley-Interscience: New York, 1983; Vol. 23, Part 4, p 279.
2. Over 1 million deaths in 1999; World Health Organization (WHO) Report 2000, World Health in Statistics, Annex Table 3.