อภิรัตน์วรากุล กรกฏ. “The EMS system in Thailand and ASEAN”. Srinagarind Medical Journal 28, no. 4 (November 27, 2013): 64–68. accessed December 8, 2025. https://li01.tci-thaijo.org/index.php/SRIMEDJ/article/view/14761.