q MSDN SQL Server Developer Center-http://www.msdn.microsoft.com/sql
q Oracle OTN-http://www.oracle.com/technology/index.html
q IBM DB2 Developer Center-http://www.ibm.com/developerworks/db2/
q Mark Logic xq:zone-http://www.xqzone.marklogic.com/
q SQL/XML specification-sqlx.org/SQL-XML-documents/5FCD-14-XML-2004-07.pdf