Stéphane Marchand-Maillet Arjen P. de Vries Mor Naaman Workshop on Information Retrieval over Social Networks. 803 2009 ECIR http://dx.doi.org/10.1007/978-3-642-00958-7_90 conf/ecir/2009 db/conf/ecir/ecir2009.html#Marchand-MailletVN09