Thorsten Fiebig Guido Moerkotte Evaluating Queries on Structure with eXtended Access Support Relations. 125-136 http://link.springer.de/link/service/series/0558/bibs/1997/19970125.htm 2000 conf/webdb/2000 WebDB (Selected Papers) db/conf/webdb/webdbs2000.html#FiebigM00a