Matthias Brantner Sven Helmer Carl-Christian Kanne Guido Moerkotte Kappa-Join: Efficient Execution of Existential Quantification in XML Query Languages. 1-15 2006 conf/xsym/2006 XSym http://dx.doi.org/10.1007/11841920_1 db/conf/xsym/xsym2006.html#BrantnerHKM06