Prasad, N. et al. 2010. Studied on Arylhydrazones, Part IX: Action of Perchloric Acid Formic Acid on Diethyl Mesoxalate Phenylhydrazones, 2,3-Dioxo-2-(Phenyl-hydrazono) Butyrate and Cyano Phenylhydrazones. Asian Journal of Chemistry. 6, 4 (Mar. 2010), 901–910.