Kalbende, P.P., and N.B. Jadhav. “K-10 Montmorillonite Catalysed Solvent Free Synthesis of Coumarins via Pechmann Condensation”. International Journal of Scientific Research in Chemical Sciences, vol. 7, no. 5, Oct. 2020, pp. 15-21, https://ijsrcs.isroset.org/index.php/j/article/view/80.