François Bry Sebastian Schaffert Towards a Declarative Query and Transformation Language for XML and Semistructured Data: Simulation Unification. 255-270 2002 conf/iclp/2002 ICLP http://dx.doi.org/10.1007/3-540-45619-8_18 db/conf/iclp/iclp2002.html#BryS02