@inproceedings{modelinglanguageproficiencyusingimplicit,
  title = {Modeling Language Proficiency Using Implicit Feedback},
  author = {Chris Hokamp and Rada Mihalcea and Peter Schuelke},
  year = {2014},
  booktitle = {LREC 2014 5},
  url = {https://aclanthology.org/L14-1090},
}