This is the official home page for DocBook: The Definitive Guide. The definitive guide, written by Norman Walsh and Leonard Muellner and published by O'Reilly & Associates, Inc., is the official documentation for DocBook.
In support of DocBook users everywhere, this book and its source SGML are available online at both this site and at OASIS. Of course, you're always free to buy a copy, too, if you'd like :-).
DocBook XSL: The Complete Guide by Bob Stayton and published by Sagehill Enterprises is the definitive guide to using the DocBook XSL stylesheets. It provides the necessary documentation to realize the full potential of DocBook publishing. It covers all aspects of DocBook publishing tools, including installing, using, and customizing the stylesheets and processing tools.
Also available: buttons, shirts, and other swag. Wear your duck on your sleeve! Well, your chest anyway.
Also check out the DocBook Wiki.
DocBook V5.0 is the official Committee Specification release of DocBook V5.0. It is a RELAX NG reimplementation of DocBook. It is a significant redesign that attempts to remain true to the spirit of DocBook.
Version 5.0 is available in RELAX NG and non-normatively in DTD and W3C XML Schema formats.
This is the “work in progress” edition of DocBook 5.0: The Definitive Guide. Version 0.0.25 documents DocBook V5.0.
This is the “work in progress” second edition of DocBook: The Definitive Guide for DocBook V4.x. Version 2.0.17 documents DocBook XML V4.5. The only change in version 2.0.17 is in the license terms; it is now available under the GNU FDL without any “Cover Text” restrictions.
DocBook is general purpose XML and SGML document type particularly well suited to books and papers about computer hardware and software (though it is by no means limited to these applications).
Version 4.5 is available in XML and SGML. Unofficial RELAX NG and W3C XML Schema versions are also available.
Version 4.5 is an OASIS Standard.
Simplified DocBook is a small subset of DocBook V4.5.
Version 1.2CR1 is available in XML DTD format.