A study of smoothing methods for language models applied to information retrieval.

ChengXiang Zhai John D. Lafferty A study of smoothing methods for language models applied to information retrieval. 179-214 2004 22 ACM Trans. Inf. Syst. 2 http://doi.acm.org/10.1145/984321.984322 db/journals/tois/tois22.html#ZhaiL04