Jina N, Thammathikul A, Chairueng N. THE MODEL OF COMPETENCY DEVELOPMENT FOR SCHOOL ADMINISTRATORS TOWARD EDUCATIONAL EXCELLENCE UNDER THE SECONDARY EDUCATIONAL SERVICE AREA OFFICE NAKHON SI THAMMARAT. JSC [internet]. 2026 May 25 [cited 2026 Sep. 28];10(5):208-1. available from: https://so06.tci-thaijo.org/index.php/JSC/article/view/293512