Haldorai, Y., G. Kalkhambkar, R. and Shim, J.-J. (2013) “Brønsted-Acidic Imidazolium Ionic Liquid [bmim(SO3H)][OTf]: A Mild Catalyst for Highly Efficient Synthesis of Coumarins”, Asian Journal of Chemistry, 25(16), pp. 9379–9383. doi: 10.14233/ajchem.2013.15772.