M. S., Ameen Abdulla, and Kavilal E. G. “Analytical Investigation of Higher Education Quality Improvement by Using Six Sigma Approach”. HighTech and Innovation Journal 3, no. 2 (February 24, 2022): 196–206. Accessed October 10, 2025. https://hightechjournal.org/index.php/HIJ/article/view/207.