“Study on Synthesis of Solid Acid Catalyst from Borassus flabellifer L. Waste with Sulfonation Method: Kajian Sintesis Katalis Asam Padat dari Limbah Sabut Siwalan (Borassus flabellifer L.) dengan Metode Sulfonasi” (2021) Journal Pharmasci (Journal of Pharmacy and Science), 6(2), pp. 89–97. doi:10.53342/pharmasci.v6i2.224.