Tunkaew S, Thammatin T, Komonmit P. Uplifting Product Standards of Chiang Saen Learning Center, Chiang Rai Rajabhat University. RJPJ [internet]. 2023 Jun. 30 [cited 2026 Sep. 28];17(52):355-70. available from: https://so05.tci-thaijo.org/index.php/RJPJ/article/view/260737