Pingkaew, N., C. Jittithavorn, C. Na Talang, and K. Pongponrat. “Behaviors, Experiences, and Needs of Senior Tourists Visiting Khao Yai National Park ”. Dusit Thani College Journal, Vol. 14, no. 3, Dec. 2020, pp. 51-77, https://so01.tci-thaijo.org/index.php/journaldtc/article/view/245492.