1. in The Alkaloids, Volume XI. Chemistry and Physiology (Ed.: , Academic Press, New York., 1968 , p. 79.
2. M. A. J. T. Van Gessel in Alkaloids: Chemical and Biological Perspectives (Ed.: , Wiley, New York, 1988 , , p. 75.
3. J. E. Saxton in The Chemistry of Heterocyclic Compounds (Ed.: Wiley, New York, 1994 , supplement to , part 4, p. 487.
4. P. Skolnick in The Alkaloids (Ed.: , Academic Press, New York, 1999 , , chapter 3, p. 197.
5. Alcaloïdes indoliques—CII