1. Association of Virtual Worlds. (2008, August). The blue book: A consumer guide to virtual worlds, (4th edition, p. 1). Retrieved on April 12, 2009, from http://www.associationofvirtualworlds.com/ pdf/Blue%20Book%204th%20Edition% 20August%202008.pdf
2. Bell, M. (2008). Toward a definition of “virtual worlds”. Journal of Virtual Worlds Research, 1(1), 2-5. Retrieved on February 3, 2009, from http://journals.tdl.org/jvwr/ article/view/283/237
3. Bersin, J. (2008, July). Today’s high-impact learning organization. Chief Learning Officer Magazine. Retrieved on July 16, 2009, from http://clomedia.com/articles/ view/today_s_high_impact_ learning_organization/1
4. Bransford, J., Brown, A., & Cocking, R. (1999). How people learn: Brain, mind experience and school. Retrieved on November 1, 2008, from http://cde.athabascau.ca/ online_book/pdf/TPOL_chp02.pdf