A. Jadhav, Santosh, et al. “Zirconia Nanoparticles Catalyzed Multi- Component Synthesis of Functionalized Chromene-Pyarazolone Derivatives”. Asian Journal of Organic & Medicinal Chemistry, vol. 1, no. 3, Oct. 2016, pp. 91-96, doi:10.14233/ajomc.2016.AJOMC-P27.