Satiansukpong, N., and A. Pongsaksri. “Study on the Relationship of Visual Perception and Intelligence : Case Study in Muang District, Chiang Mai”. Journal of Associated Medical Sciences, vol. 30, no. 3, Feb. 2015, p. 183, https://he01.tci-thaijo.org/index.php/bulletinAMS/article/view/60409.