Goud, G. U., J. Prakash, A. Kumar, G. Reddy, and M. Krishna. “Formulation and Design of Metformin Hydrochloride Extended Release Tablets”. PharmaTutor, Vol. 2, no. 11, Nov. 2014, pp. 112-9, http://www.pharmatutorjournal.com/index.php/pt/article/view/223.