Manolis Koubarakis Kostis Kyzirakos Modeling and Querying Metadata in the Semantic Sensor Web: The Model stRDF and the Query Language stSPARQL. 425-439 2010 ESWC (1) http://dx.doi.org/10.1007/978-3-642-13486-9_29 conf/esws/2010-1 db/conf/esws/eswc2010-1.html#KoubarakisK10