1. Alha, K., Koskinen, E., Paavilainen, J., Hamari, J., & Kinnunen, J. (2014). Free-to-play games: Professionals’ perspectives. In DiGRA Nordic '14: Proceedings of the 2014 International DiGRA Nordic Conference.
2. Alinsky, S. D. (1972). Rules for radicals. A pragmatic primer for realistic radicals. New York: Vintage Books.
3. Anderson, C. (2009). Free: The future of a radical price. New York: Random House.
4. Bartle, R. A. (2014). Design principles: Use and misuse. In T. Quandt & S. Kröger (Eds.), Multiplayer: The social aspects of digital gaming (pp. 10–22). New York: Routledge.
5. Bate, P., & Robert, G. (2006). Experience-based design: from redesigning the system around the patient to co-designing services with the patient. Quality and Safety in Heath Care, 15, 307–310. https://doi.org/10.1136/qshc.2005.016527