Khakwani, Samia, et al. “Mass Spectrometry of Substituted Ethyl-4-anilinopyrazolo[3,4-b]pyridine-5-Carboxylates”. Asian Journal of Chemistry, vol. 28, no. 4, Dec. 2015, pp. 789-92, doi:10.14233/ajchem.2016.19477.