Ralph Ribeiro, David Oliveira, Leandro Carvalho, and Elaine Oliveira. 2018.
 Gamification of an Online Judge System to Motivate Students in Introductory Programming. In <em>Proceedings of the 29th Brazilian Symposium on Computers in Education</em>, October 29, 2018, Fortaleza/CE, Brasil. SBC, Porto Alegre, Brasil, 805-814. DOI: <a href="https://doi.org/10.5753/cbie.sbie.2018.805">https://doi.org/10.5753/cbie.sbie.2018.805</a>.