Kossay K. Al-Ahmady, D., and H. Haqe Ismaeel. “Effect of Using Anaerobic Selectors on the Performance of Continuous Flow Activated Sludge Systems”. Al-Rafidain Engineering Journal (AREJ), vol. 21, no. 6, Dec. 2013, pp. 88-99, doi:10.33899/rengj.2013.82367.