Ricardo A. Baeza-Yates Carlos Castillo Flavio Junqueira Vassilis Plachouras Fabrizio Silvestri Challenges on Distributed Web Retrieval. 6-20 2007 conf/icde/2007 ICDE http://dx.doi.org/10.1109/ICDE.2007.367846 db/conf/icde/icde2007.html#Baeza-YatesCJPS07