Thongpoyai S, Piampuchana N. STRATEGIC LEADERSHIP OF SCHOOL ADMINISTRATORS AFFECTING THE EFFECTIVENESS OF SCHOOLS UNDER UDON THANI SECONDARY EDUCATIONAL SERVICE AREA OFFICE. JBER [internet]. 2023 Mar. 31 [cited 2026 Oct. 8];9(1):1-14. available from: https://so06.tci-thaijo.org/index.php/jber/article/view/263398