Srichiangsa, W. and Art-in , S. (2026) “THE DEVELOPMENT OF ENGLISH SPEAKING ABILITY USING FLIPPED CLASSROOM WITH DUOLINGO FOR FIRST-YEAR VOCATIONAL CERTIFICATE STUDENTS”, Academic Journal Phranakhon Rajabhat University, 17(1), pp. 47–61. available at: https://so01.tci-thaijo.org/index.php/AJPU/article/view/285560 (accessed: 13 September 2026).