1. Becker, W. E. (1997). Teaching economics to undergraduates. Journal of Economic Literature, 35(3), 1347–73.
2. Bonk, C. J., & Dennen, V. P. (2005). Massive multiplayer online gaming: A research framework for military education and training. (Technical Report # 2005–1). Washington, DC: U.S. Department of Defense (DUSD/R): Advanced Distributed Learning (ADL) Initiative.
3. Castronova, E. (2002). On virtual economies. Center for Economic Studies and Ifo Institute for Economic Research. CESifo Working Paper No. 752. Retrieved from http://papers.ssrn.com/sol3/papers.cfm?abstract_id=338500
4. Cohen, P. (2008) World of Warcraft adds another half million subscribers. The Industry Standard. Retrieved from http://www.thestandard.com/news/2008/12/24/world-warcraft-adds-another-half-million-subscribers
5. Dieterle, E., & Clarke, J. (2008). Multi-user virtual environments for teaching and learning. In M. Pagani (Ed.), Encyclopedia of multimedia technology and networking (2nd ed). Hershey, PA: Idea Group, Inc.