HENG, K.; SOL, K. Online learning during COVID-19: Key challenges and suggestions to enhance effectiveness. Cambodian Journal of Educational Research, [S. l.], v. 1, n. 1, p. 3–16, 2021. DOI: 10.62037/cjer.2021.01.01.02. Disponível em: https://cjerjournal.com/index.php/cjer/article/view/8. Acesso em: 13 nov. 2026.