Sattar Aldabagh, D., E. M.Ghazal, and A. M.Yaseen. “A Study of Factors Affecting Drain Spacing Calculated With Different Methods”. Al-Rafidain Engineering Journal (AREJ), vol. 19, no. 4, Aug. 2011, pp. 63-77, doi:10.33899/rengj.2011.26777.