@InProceedings{wang-EtAl:2014:EMNLP20143,
  author    = {Wang, Quan  and  Liu, Jing  and  Wang, Bin  and  Guo, Li},
  title     = {A Regularized Competition Model for Question Difficulty Estimation in Community Question Answering Services},
  booktitle = {Proceedings of the 2014 Conference on Empirical Methods in Natural Language Processing (EMNLP)},
  month     = {October},
  year      = {2014},
  address   = {Doha, Qatar},
  publisher = {Association for Computational Linguistics},
  pages     = {1115--1126},
  url       = {http://www.aclweb.org/anthology/D14-1118}
}