Jaratjarungkiat, Sureenate. β€œIs the Copula /pen/ In Thai Meaningless?”. Journal of Mekong Societies 15, no. 2 (August 28, 2019): 1–17. Accessed October 3, 2022. https://so03.tci-thaijo.org/index.php/mekongjournal/article/view/174496.