C. Walker, and H. Wiesenfeld. Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America, (April 2007)PMID: 17342664.
W. van Diggelen, and M. Overdijk. Computers in Human Behavior, 25 (5):
1056 - 1066(2009)Including the Special Issue: Design Patterns for Augmenting E-Learning Experiences.