Exploring indicators of engagement: applications for gamification of online training systems. Periodicals of Engineering and Natural Sciences, [S. l.], v. 8, n. 4, 2020. DOI: 10.21533/pen.v8.i4.1381. Disponível em: https://pen.ius.edu.ba/index.php/pen/article/view/1381. Acesso em: 17 jun. 2026.