CHANDRA SEKHAR BVVN, et al. “Novel Synthetic Approaches For The Synthesis Of Montelukast Sodium; Syntheis And Characterization Of Impurities”. International Journal of Pharma and Bio Sciences, vol. 2, no. 3, Sept. 2011, pp. 417-25, https://ijpbs.net/index.php/journal/article/view/915.