Nurhayati Mohd Nur, Ahmad Furqan Mohd Yusuf, Nur Nabilah Mohd Yusof. “Physical Fatigue and Work-Related Musculoskeletal Disorders Among Air Traffic Controllers (ATCOs)”. International Journal of Advanced Science and Technology, Vol. 29, no. 06, Apr. 2020, pp. 156 -1, http://sersc.org/journals/index.php/IJAST/article/view/11308.