Stefano Spaccapietra Lina Al-Jadir Shijun Yu Somebody, Sometime, Somewhere, Something. 6-16 2005 conf/udm/2005 UDM http://doi.ieeecomputersociety.org/10.1109/UDM.2005.20 db/conf/udm/udm2005.html#SpaccapietraAY05