F. K. I. Idan and S. M. Obyed, “Treatment of Waste Extract Lubricating Oil by Catalytic Cracking Process to Produce Light Fractions”, alkej, vol. 15, no. 2, pp. 100–107, May 2019, Accessed: Jan. 08, 2026. [Online]. Available: https://www.alkej.uobaghdad.edu.iq/index.php/alkej/article/view/552