Fanguy, Mik, Jamie Costley, and Matthew Baldwin. “Pinch Hitter: The Effectiveness of Content Summaries Delivered by a Guest Lecturer in Online Course Videos”. The International Review of Research in Open and Distributed Learning 18, no. 7 (November 29, 2017). Accessed April 20, 2019. http://www.irrodl.org/index.php/irrodl/article/view/3208.