Ubong, A. Iboh, T. Ebong Samuel, W.Robert Ubong, Christopher F. Sandy, and John A. Efiang. 2023. “Determination of the Density and Viscosity of Engine Oil With Grade 20w-50 in Nigeria”. International Journal of Natural and Practical Sciences (IJNPS) 5 (1):1-11. http://icidr.org.ng/index.php/Ijnps/article/view/529.