Nattakarn Ratprasartporn Jonathan Po Ali Cakmak Sulieman Bani-Ahmad Gultekin Özsoyoglu Context-based literature digital collection search. 277-301 2009 18 VLDB J. 1 http://dx.doi.org/10.1007/s00778-008-0099-9 db/journals/vldb/vldb18.html#RatprasartpornPCBO09