Mohammed, Abdul-Halim A-K, Riyadh H Hassan, and Karim H Hassan. “Catalytic Pour Point Reduction and Viscosity Improvement of Lubricating Oil Fractions Using Sulfided Nickel-Tungsten Catalysts”. Iraqi Journal of Chemical and Petroleum Engineering 4, no. 1 (March 30, 2003): 41–46. Accessed September 17, 2024. https://ijcpe.uobaghdad.edu.iq/index.php/ijcpe/article/view/660.