1. C. Pérez-Medina , M.Pérez-Torralba, C.López, R. M.Claramunt, P.Nioche and C. S.Raman, XIV Congreso Nacional de la Sociedad Española de Química Terapeútica, Bilbao, Spain, 2005
2. J. Elguero , C.Marzin, A. R.Katritzky and P.Linda, The Tautomerism of Heterocycles, Academic Press, New York, 1976, pp. 655
3. The Tautomerism of Heterocycles: Five-membered Rings with Two or More Heteroatoms
4. The use of NMR spectroscopy to study tautomerism