Muhali, Muhali, et al. “Effectiveness of Activated Carbon CaCl2 and NaNO3 Reducing Fatty Acids and Increasing the Quantity of Biodiesel Production”. Jurnal Penelitian Pendidikan IPA, vol. 9, no. 1, Jan. 2023, pp. 257-64, doi:10.29303/jppipa.v9i1.2624.