1. 1Klaman, D. Lubricants and Related Products, 1983, pp. 84‐5.
2. 3Doull, J., Klaassen, D.D. and Amdur, M.O. Toxicology: Hazardous Effects of Heavy Metals, 2nd ed., Macmillan, New York, NY, 1980.
3. 12Amiry, M.N. and Aban, M.M. Ways and Means of Utilization of Used Lubricating Oil, GSPLAJ, research report, Petroleum Research Centre, Tripoli, 1987.