Dimitri Theodoratos Theodore Dalamagas Pawel Placek Stefanos Souldatos Timos K. Sellis Containment of Partially Specified Tree-Pattern Queries. 3-12 2006 conf/ssdbm/2006 SSDBM http://doi.ieeecomputersociety.org/10.1109/SSDBM.2006.16 db/conf/ssdbm/ssdbm2006.html#TheodoratosDPSS06