Wim F. J. Verhaegh Aukje E. M. van Duijnhoven Pim Tuyls Jan H. M. Korst Privacy Protection in Memory-Based Collaborative Filtering. 61-71 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3295&spage=61 2004 conf/eusai/2004 EUSAI db/conf/eusai/eusai2004.html#VerhaeghDTK04