Zografoula Vagena Nick Koudas Divesh Srivastava Vassilis J. Tsotras Efficient Handling of Positional Predicates Within XML Query Processing. 68-83 2005 conf/xsym/2005 XSym http://dx.doi.org/10.1007/11547273_6 db/conf/xsym/xsym2005.html#VagenaKST05