The ABCs of XML : the librarian's guide to the extensible markup language / by Norman Desmarais.

XML and SGML
XML document structure
Doing it with style
Pointing and linking
Processing XML data
Managing XML documents
XML and its potential for e-commerce
Getting started
Bibliography
Glossary
Appendix 1. Library of Congress' SGML format
Appendix 2. Bibliographic record in XML format
Appendix 3. USMARC record converted from XML
Appendix 4. XML format for bibliographic data.