1. R.L. Chaney. Land Application of Sewage Sludge. Association for the Utilization of Sewage Sludge, Tokyo, 1988, pp.77-105.
2. The Amount of Heavy Metals Derived from Domestic Wastewater
3. Bulletin de l’Institut scientifique;Kao;Rabat, section Sciences de la Vie.,2007
4. Martigne, and Seguret;Cauchi;Techniques, Sciences et Méthodes.,1996