Shafqat, S. S., Khan, A. A., Khan, M. A., Salleh, S. F., Jamaludin, M. S., & Cem, P. S. (2016). Green Synthesis and Characterization of 3-Carboxycoumarin and Ethylcoumarin-3-carboxylate via Knoevenagel Condensation. Asian Journal of Chemistry, 29(2), 261–266. https://doi.org/10.14233/ajchem.2017.20142