Dimitrios Katsaros Efficiently Maintaining Structural Associations of Semistructured Data. 118-132 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2563&spage=118 2001 conf/pci/2001 Panhellenic Conference on Informatics db/conf/pci/pci2001.html#Katsaros01