Frederik De Keukelaere Thomas DeMartini Jeroen Bekaert Rik Van de Walle Supporting rights checking in an MPEG-21 Digital Item Processing environment. 1062-1065 2005 conf/icmcs/2005 ICME http://doi.ieeecomputersociety.org/10.1109/ICME.2005.1521608 db/conf/icmcs/icme2005.html#KeukelaereDBW05