@InProceedings{ehara-EtAl:2012:PAPERS,
  author    = {Ehara, Yo  and  Sato, Issei  and  Oiwa, Hidekazu  and  Nakagawa, Hiroshi},
  title     = {Mining Words in the Minds of Second Language Learners: Learner-Specific Word Difficulty},
  booktitle = {Proceedings of COLING 2012},
  month     = {December},
  year      = {2012},
  address   = {Mumbai, India},
  publisher = {The COLING 2012 Organizing Committee},
  pages     = {799--814},
  url       = {http://www.aclweb.org/anthology/C12-1049}
}