Worrakawin, K., C. . Na Thalang, S. . Wongmonta, and T. . Ratanapongtra. “Perceptual Tourism in Sandstone Geomorphology of Pa-Tam National Park, Ubon Ratchathani Province”. Rajapark Journal, vol. 14, no. 35, Aug. 2020, pp. 47-60, https://so05.tci-thaijo.org/index.php/RJPJ/article/view/241161.