Santos Espino, José Miguel, Cayetano Guerra Artal, and Sara María González Betancor. “Video Lectures: An Analysis of Their Useful Life Span and Sustainable Production”. The International Review of Research in Open and Distributed Learning 22, no. 3 (April 28, 2021): 99–118. Accessed April 19, 2024. https://www.irrodl.org/index.php/irrodl/article/view/5553.