János Demetrovics Gyula O. H. Katona Dezsö Miklós On the Security of Individual Data. 49-58 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2942&spage=49 2004 conf/foiks/2004 FoIKS db/conf/foiks/foiks2004.html#DemetrovicsKM04