Mahmud, N. R. A., N. Muhammad, and Nurhalifah. “Effect of the Adding of Natural Antioxidant in the Stored Traditional Coconut Oil on the Free Fatty Acid Value”. Proceeding International Conference on Science and Engineering, vol. 4, Feb. 2021, pp. 76-79, http://sunankalijaga.org/prosiding/index.php/icse/article/view/624.