Y. Chen, H. Dong, and W. Wang. Proceedings of the 2018 International Conference on Data Science and Information Technology, page 138--143. New York, NY, USA, ACM, (2018)
X. Wei, and B. Croft. SIGIR '06: Proceedings of the 29th annual international ACM SIGIR conference on Research and development in information retrieval, page 178--185. New York, NY, USA, ACM Press, (2006)