1. Möhlau, R.Ber.
1881, 14, 171–175.
2. Bischler, A.; Fireman, P. Ber.
1893, 26, 1346–1349.
3. Sundberg, R. J. The Chemistry of Indoles;Academic Press: New York, 1970, pp 164. (Book).
4. Buu-Hoï, N. P.; Saint-Ruf, G.; Deschamps, D.; Bigot, P. J. Chem. Soc. (C)
1971, 2606–2609.
5. Houlihan, W. J., Ed.; The Chemistry of Heterocyclic Compounds, Indoles (Part 1),Wiley & Sons: New York, 1972. (Book).