อัตไพบูลย์ ภัทรัต. “Economic Linkages Among Border Provinces in the South of the Lower Northeastern Region”. Journal of Graduate School, Pitchayatat, Ubon Ratchathani Rajabhat University 15, no. 2 (August 26, 2020): 125–137. Accessed May 4, 2024. https://so02.tci-thaijo.org/index.php/Pitchayatat/article/view/229701.