@article(2007-n-gram-vs-keyword-based-passage-retrieval-for-question-answering,
  author = {Davide Buscaldi and Paolo Rosso and Emilio Sanchis Arnal},
  title = {N-gram vs. Keyword-based Passage Retrieval for Question Answering},
  year = {2007},
  journal = {Lecture Notes in Computer Science},
  volume = {4730},
  pages = {377-384}
)