For more information on XML, from basics to advanced, all of the following are excellent resources.
Perfect XML. The PerfectXML Web site is designed to help you learn XML technologies and use them in your applications.
http://www.perfectxml.com/default.asp
w3schools XML Tutorial. In this XML tutorial you will learn what XML is, and the difference between XML and HTML. You will also learn how to start using XML in your applications.
http://www.w3schools.com/xml/default.asp
Microsoft MSDN XML.The comprehensive resource for Microsoft’s XML tools. Probably not where you want to start if you are a beginner.
http://msdn.microsoft.com/library/default.asp?url=/nhp/default.asp?contentid=28000438
XML in Libraries. Article: How Does XML Help Libraries?
http://www.infotoday.com/cilmag/sep02/Banerjee.htm
XML in a Nutshell, Third Edition
by W. Scott Means, Elliotte Rusty Harold
O'Reilly & Associates; ISBN: 0596007647; 3rd edition (September 2004)
http://www.oreilly.com/catalog/xmlnut3/
XSLT
by Doug Tidwell (Paperback)
O'Reilly & Associates; ISBN: 0596000537; 1st edition (August 2001)
http://www.oreilly.com/catalog/xslt/
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