Samitsomboon M. A STUDY OF SELF-DISCIPLINE OF VOCATIONAL CERTIFICATE STUDENTS IN PRE-ENGINEERING COURSE. Res Comm Soc Dev J [internet]. 2023 Jun. 28 [cited 2026 Sep. 17];17(2):180-9. available from: https://so04.tci-thaijo.org/index.php/NRRU/article/view/265272