1. Gamification;Hamari,2007
2. For the Win;Hunter,2012
3. From game design elements to gamefulness: defining “gamification”;Deterding,2011
4. Is it all a game? Understanding the principles of gamification;Robson;Bus. Horiz.,2015
5. StackOverflow and GitHub: Associations between software development and crowdsourced knowledge;Vasilescu,2013