د. علي خليفه الشيخ عبد الله, and د. ياسر تاج السر محمد سند. 2020. “The Effect of Using Six Sigma Methodology Standards in Improving the Performance of the Internal Control System: A Field Study on Government Units in Algezira State”. White Nile Journal for Studies and Research, no. 16 (September):81-105. https://doi.org/10.67135/wnj.2020.1604.