Assadi, S., J. Hsu, and S. Jabbari. “Online Assignment of Heterogeneous Tasks in Crowdsourcing Markets”. Proceedings of the AAAI Conference on Human Computation and Crowdsourcing, vol. 3, no. 1, Sept. 2015, pp. 12-21, doi:10.1609/hcomp.v3i1.13236.