Azarakhsh Malekian Chi-Chao Chang Ravi Kumar Grant Wang Optimizing query rewrites for keyword-based advertising. 10-19 2008 ACM Conference on Electronic Commerce http://doi.acm.org/10.1145/1386790.1386793 conf/sigecom/2008 db/conf/sigecom/sigecom2008.html#MalekianCKW08