Surachai Jansri, Gumpon Prateepchaikul, and Sukritthira B. Ratanawilai. “Acid-Catalyzed Esterification: A Technique for Reducing High Free Fatty Acid in Mixed Crude Palm Oil”. Agriculture and Natural Resources 41, no. 3 (September 30, 2007): 555–560. accessed October 9, 2026. https://li01.tci-thaijo.org/index.php/anres/article/view/244280.