Balleras JM, Yippikun C, Castro RB, Prasertsak A. Developing a standardized English proficiency test based on the CEFR and language test development manual. JEL [internet]. 2025 Aug. 16 [cited 2025 Oct. 9];6(2):169-8. available from: https://so17.tci-thaijo.org/index.php/JEL/article/view/1007