Esichaikul, R., Chansawang, R., Songsoonthornwong, C., & Kaewudom, Y. (2020). The Study and Revision of the Tourist Guide and Tour Leader Training Courses. University of the Thai Chamber of Commerce Journal Humanities and Social Sciences, 40(2), 1–30. retrieved from https://so06.tci-thaijo.org/index.php/utccjournalhs/article/view/224478