Yao, Weilong, Jing He, Hua Wang, Yanchun Zhang, and Jie Cao. 2015. “Collaborative Topic Ranking: Leveraging Item Meta-Data for Sparsity Reduction”. Proceedings of the AAAI Conference on Artificial Intelligence 29 (1). https://doi.org/10.1609/aaai.v29i1.9151.