Sonja Zillner Bernhard Haslhofer Werner Winiwarter The Design and Implementation of a Query Algebra of Multimedia Meta Objects. 537-542 2005 conf/dexaw/2005 DEXA Workshops http://dx.doi.org/10.1109/DEXA.2005.183 db/conf/dexaw/dexaw2005.html#ZillnerHW05