Matthias Bender Tom Crecelius Mouna Kacimi Sebastian Michel Josiane Xavier Parreira Gerhard Weikum Peer-to-Peer Information Search: Semantic, Social, or Spiritual? 51-60 2007 30 IEEE Data Eng. Bull. 2 http://sites.computer.org/debull/A07june/bender.pdf db/journals/debu/debu30.html#BenderCKMPW07