1. Attwood, J.: The Gamification, Coding Horror (October 12, 2011),
http://blog.codinghorror.com/the-gamification/
2. Boese, S.: Scoring Serious Results Through Gamification. HREOnline.com (May 13, 2013),
http://www.hreonline.com/HRE/print.jhtml?id=534355401
3. Bogost, I.: Persuasive Games: Exploitationware. Gamasutra (May 3, 2011),
http://www.gamasutra.com/view/feature/6366/persuasive_games_exploitationware.php
4. Carse, J.: Finite and Infinite Games. Ballantine, New York (1986)
5. Deterding, S., Dixon, D., Khaled, R., Nacke, L.: From Game Design Elements to Gamefulness: Defining “Gamification”. In: MindTrek 2011, pp. 9–15. ACM Press, New York (2011)