Ixent Galpin Christian Y. A. Brenninkmeijer Farhana Jabeen Alvaro A. A. Fernandes Norman W. Paton Comprehensive Optimization of Declarative Sensor Network Queries. 339-360 2009 SSDBM http://dx.doi.org/10.1007/978-3-642-02279-1_26 conf/ssdbm/2009 db/conf/ssdbm/ssdbm2009.html#GalpinBJFP09