M. M. Zainol, M. N. F. Roslan, M. Asmadi, dan N. A. S. Amin, “Preparation and Characterization of Sulfonated Carbon Cryogel Doped Zinc as a Catalyst for Glucose Ethanolysis to Ethyl Levulinate”, vol. 21, no. 1, hlm. 1-10, Jun 2021.