AJITHA, M., et al. “Synthesis and Evaluation of New 3-Substituted[3,4-Dihydro pyrimidinones]indolin-2-Ones for Antioxidant Activity”. Asian Journal of Chemistry, vol. 21, no. 6, Mar. 2010, pp. 4635-42, https://asianpubs.org/index.php/ajchem/article/view/18211.