Philip Guo, edX, 10/29/2013: Optimal length = 6 min. or shorter
Melanie Hibbert, EDUCAUSE Review, 4/7/2014
Eric Tremblay, E-Learning Acupuncture, 3/19/2014
Miguel Guhlin, 8/25/2013: his notes from a series of JOLT articles
Emily Moore, Faculty Focus, 5/20/2013