Wai Gen Yee Linh Thai Nguyen Ophir Frieder Alternatives to conjunctive query processing in peer-to-peer file-sharing systems. 1737-1741 2009 SAC http://doi.acm.org/10.1145/1529282.1529671 conf/sac/2009 db/conf/sac/sac2009.html#YeeNF09