Sreenivasa Rao, Battula, et al. “Development and Validation of A Reverse Phase HPLC Method for the Determination of Metformin HCl in Pharmaceutical Dosage Forms”. Asian Journal of Chemistry, vol. 24, no. 12, Aug. 2012, pp. 5460-2, https://asianpubs.org/index.php/ajchem/article/view/9904.