SURESH, N., et al. “Formulation and Evaluation of Oral Sustained Release Suspensions Using Ethyl Cellulose Microcapsules Containing Propranolol Hydrochloride Using Ion Exchange Resinates”. Asian Journal of Chemistry, vol. 19, no. 4, Mar. 2010, pp. 2757-63, https://asianpubs.org/index.php/ajchem/article/view/13374.