Muhammed Zakir Hossain, and Sayaka Zaman. “Statistical Process Control (SPC) As a Tool for Measuring Customer Dissatisfaction Level and Service Process Improvement”. Global Journal of Management and Business Research 19, no. A3 (March 15, 2019): 29–36. Accessed April 28, 2024. https://journalofbusiness.org/index.php/GJMBR/article/view/2708.