Ranee Esichaikul ร. อ., and Rochaporn Chansawang ร. จ. “Development of Ecotourism Attraction Standards in Thailand”. Dusit Thani College Journal, vol. 11, no. special, July 2018, pp. 1-17, https://so01.tci-thaijo.org/index.php/journaldtc/article/view/135742.