1. Gamification: toward a definition;Deterding,2011
2. From game design elements to gamefulness: defining gamification;Deterding,2011
3. Y. Xu, Literature Review on Web Application Gamification and Analytics. Honolulu, HI, 2011, pp. 11–05.
4. Game-Based Marketing: Inspire Customer Loyalty Through Rewards, Challenges, and Contests;Zichermann,2010
5. (Re) defining gamification: a process approach;Werbach,2014