Laononkhro, B., and P. Chairatana. “Organizational Commitment and Job Motivation of Traffic Officers in Traffic Operation Department at State Railway of Thailand”. Research and Development Journal, Loei Rajabhat University, vol. 15, no. 53, Aug. 2020, pp. 21-31, https://so05.tci-thaijo.org/index.php/researchjournal-lru/article/view/242211.