เพ็งทอง เ. “Factors That Are Affecting the Health-Related Tourism to Foreign Tourists of Koh Samui District, Surat Thani Province”. Pathumthani University Academic Journal, vol. 11, no. 1, June 2019, pp. 267-7, https://so05.tci-thaijo.org/index.php/ptujournal/article/view/187782.