KhudaBukhsh, A., J. Carbonell, and P. Jansen. “Detecting Non-Adversarial Collusion in Crowdsourcing”. Proceedings of the AAAI Conference on Human Computation and Crowdsourcing, vol. 2, no. 1, Sept. 2014, pp. 104-11, doi:10.1609/hcomp.v2i1.13157.