CONRAD, Dianne. Cognitive, Instructional, and Social Presence as Factors in Learners’ Negotiation of Planned Absences from Online Study. The International Review of Research in Open and Distributed Learning, [S. l.], v. 10, n. 3, 2009. DOI: 10.19173/irrodl.v10i3.630. Disponível em: https://www.irrodl.org/index.php/irrodl/article/view/630. Acesso em: 17 apr. 2024.