Preepremmote, Patcharee, Pimthong Thongnopkun, Worachai Roubroumlert, Dawan Madlee, Alongkorn Pamounsub, and Parichat Tengsuwan. “Value-Added Creation to Enhance the Income of Gem and Jewelry Businesses in Chanthaburi”. NIDA Business Journal, no. 30 (December 13, 2022): 123–141. accessed April 25, 2025. https://so10.tci-thaijo.org/index.php/NIDABJ/article/view/72.