L. Buchori, D. D. Anggoro, and A. Ma’ruf "Biodiesel Production from Methanolysis of Lard Using CaO Catalyst Derived from Eggshell: Effects of Reaction Time and Catalyst Loading", Advances in Science, Technology and Engineering Systems Journal, vol. 6, no. 2, pp. 399–404, 2021, doi: 10.25046/aj060246.