Yin Yang Nilesh Bansal Wisam Dakka Panagiotis G. Ipeirotis Nick Koudas Dimitris Papadias Query by document. 34-43 2009 WSDM http://doi.acm.org/10.1145/1498759.1498806 conf/wsdm/2009 db/conf/wsdm/wsdm2009.html#YangBDIKP09