Diogo S. Martins Mauro Biajiz Antônio Francisco do Prado Wanderley Lopes de Souza Implicit relevance feedback for context-aware information retrieval in UbiLearning environments. 659-663 2009 SAC http://doi.acm.org/10.1145/1529282.1529418 conf/sac/2009 db/conf/sac/sac2009.html#MartinsBPS09