Cheng, Jinn-Shing, Echo Huang, and Chuan-Lang Lin. “An E-Book Hub Service Based on a Cloud Platform”. The International Review of Research in Open and Distributed Learning 13, no. 5 (November 1, 2012): 39-55. Accessed December 5, 2020. http://www.irrodl.org/index.php/irrodl/article/view/1251.