Charan Guguloth, Vijaya, and Satyanarayana Battu. “Synthesis of Some Aromatic and Aliphatic Esters Using WO3 ZrO2 Solid Acid Catalyst under Solvent Free Conditions”. Asian Journal of Chemistry, vol. 32, no. 9, Aug. 2020, pp. 2153-7, doi:10.14233/ajchem.2020.22683 .