Linda Pareschi Daniele Riboni Alessandra Agostini Claudio Bettini Composition and Generalization of Context Data for Privacy Preservation. 429-433 2008 PerCom http://doi.ieeecomputersociety.org/10.1109/PERCOM.2008.47 conf/percom/2008 db/conf/percom/percom2008.html#PareschiRAB08