Supromajakr, Intira, Panruethai Putthongsri, Phromphong Mahapornpong, and Wisitsiri Chusakul. 2022. “Strategy Development to Promote Tourism in a Second Tiercity at Chiangkhan, Loei Province”. Dhammathas Academic Journal 22 (3):107-16. https://so06.tci-thaijo.org/index.php/dhammathas/article/view/254887.