I. . S. H. El-durssi, I. . O.S. El-Awami, G. . S. mahmoud, and F. A. Benkhaial, “Experimental Studies on the effects of chlorpyrifos on Rats IV. Biochemical changes in level of certain enzymes”, MJSc, vol. 14, no. 1, pp. 9–17, Apr. 2007.