Hernandez Delgado MJ, Pérez Pérez A, Orellana A. Three-dimensional matrix for an approximation to quality assurance in distance education. educareupelipb [Internet]. 2007 Oct. 29 [cited 2026 Nov. 9];11(2). Available from: https://www.revistas.investigacion-upelipb.com/index.php/educare/article/view/325