Weimin He Leonidas Fegaras David Levine Indexing and Searching XML Documents Based on Content and Structure Synopses. 58-69 2007 conf/bncod/2007 BNCOD http://dx.doi.org/10.1007/978-3-540-73390-4_7 db/conf/bncod/bncod2007.html#HeFL07