Ashrafi, M., J. A. Chowdhury, and M. S. Reza. “Controlled Release of Metformin Hydrochloride I. In Vitro Release from Physical Mixture Containing Xanthan Gum As Hydrophilic Rate Retarding Polymer”. Dhaka University Journal of Pharmaceutical Sciences, vol. 4, no. 1, June 2007, doi:10.3329/dujps.v4i1.200.