Lertkultanon, Y., M. Chatawanich, S. Chatawanich, and K. Montreesuksirikul. “The 9As Strategy for Sustainable Management of Man-Made Attractions: a Case Study of Ba Na Hills, Vietnam”. Dusit Thani College Journal, vol. 17, no. 2, Aug. 2023, pp. 181-94, https://so01.tci-thaijo.org/index.php/journaldtc/article/view/269368.