THAHER, K. Professional Requirements for Secondary School Principals in The Light Of 21st Century Competencies . INTERNATIONAL JOURNAL OF RESEARCH IN EDUCATION METHODOLOGY, [S. l.], v. 11, p. 55–63, 2020. DOI: 10.24297/ijrem.v11i.8692. Disponível em: https://rajpub.com/index.php/ijrem/article/view/8692. Acesso em: 21 oct. 2021.