Pitaktepsombati, Pichit, and Wanpen Vorklarng. “Who Returned Postcard in the Poll”. Journal of Population and Social Studies [JPSS] 3, no. 1-2 (May 10, 2023): 145–150. Accessed May 19, 2024. https://so03.tci-thaijo.org/index.php/jpss/article/view/268453.