Sumneing, P., Srisopachit, P., Krimjai, N. and Deesukanan, C. (2021) “The Causal Factors That Influence the Performance of Competition in the Road Freight Service Business Operators in Thailand”, Ph.D. in Social Sciences Journal, 11(1), pp. 161–174. available at: https://so05.tci-thaijo.org/index.php/phdssj/article/view/186934 (accessed: 21 September 2026).