This presentation: http://www.cafeconleche.org/slides/sd2002west/xlinks
XML Base Specification: http://www.w3.org/TR/xmlbase
XPath Specification: http://www.w3.org/TR/xpath
XML in a Nutshell
Elliotte Rusty Harold and W. Scott Means
O'Reilly & Associates, 2001
ISBN 0-596-00058-8
XPath: http://www.oreilly.com/catalog/xmlnut/chapter/ch09.html
XML Bible, second edition
Elliotte Rusty Harold
Hungry Minds, 2001
ISBN 0-7645-4760-7
XLinks: http://www.cafeconleche.org/books/bible2/chapters/ch19.html
XPointers: http://www.cafeconleche.org/books/bible2/chapters/ch20.html