M. Kusner, Y. Sun, N. Kolkin, and K. Weinberger. Proceedings of the 32Nd International Conference on International Conference on Machine Learning - Volume 37, page 957--966. JMLR.org, (2015)
T. Kenter, and M. de Rijke. Proceedings of the 24th ACM International on Conference on Information and Knowledge Management, page 1411--1420. New York, NY, USA, ACM, (2015)