title: from tree patterns to generalized tree patterns : on efficient evaluation of xquery. authors: z chen , h jagadish , l lakshmanan , s paparizos. venue: vldb. year: 2003
title: tree logical classes for efficient evaluation of xquery. authors: s paparizos , y wu , lvs lakshmanan , hv jagadish. venue: proc . sigmod conf ,. year: 2004.0