Alpa Jain Panagiotis G. Ipeirotis AnHai Doan Luis Gravano Join Optimization of Information Extraction Output: Quality Matters! 186-197 2009 ICDE http://dx.doi.org/10.1109/ICDE.2009.138 conf/icde/2009 db/conf/icde/icde2009.html#JainIDG09