BLACK, D. B. Farewell, Drop-Out: Hello, Drop-In. Canadian Journal of Higher Education, [S. l.], v. 2, n. 1, p. 31–37, 1972. Disponível em: https://www.cjhe.test.sfulib7.publicknowledgeproject.org/index.php/cjhe/article/view/182550. Acesso em: 4 may. 2026.