บุญภิละ นวรัตน์. “Designing and developing of pearl decorative souvenir; Ban Nonglad, Thonnalab sub-district, Ban Dung District, Udon Thani province”. Mahachula Academic Journal 6, no. ฉบับพิเศษ (May 20, 2019): 51–65. accessed October 6, 2026. https://so04.tci-thaijo.org/index.php/JMA/article/view/181005.