Jock A. A., Magomya A. M., and Essang S. E. “RECYCLING AND CHARACTERIZATION OF SPENT ENGINE OIL USING TWO STAGES: SOLVENT EXTRACTION AND CLAY PERCOLATION TECHNIQUES”. FUDMA JOURNAL OF SCIENCES, Vol. 7, no. 3, June 2023, pp. 182 -85, doi:10.33003/fjs-2023-0703-1836.