Reeves, Neal, Peter West, and Elena Simperl. “"A Game Without Competition Is Hardly a Game": The Impact of Competitions on Player Activity in a Human Computation Game"”. Proceedings of the AAAI Conference on Human Computation and Crowdsourcing 6, no. 1 (June 15, 2018): 154-163. Accessed September 18, 2024. https://ojs.aaai.org/index.php/HCOMP/article/view/13329.