This is not the current version of DocBook.
DocBook 4.2CR1 is available as a zip archive.
You can also retrieve the files individually if you prefer:
The DocBook V4.2CR1 README.
The DocBook DTD.
The DocBook XML DTD. The SGML version of DocBook V4.2 is a customization layer of the XML version, so it includes the complete XML release as well.
The DocBook XML DTD “information pool” module.
The DocBook XML DTD “hierarchy” module.
The DocBook XML DTD “notations” module.
The DocBook XML DTD “character entities” module.
The DocBook XML DTD “general entities” module.
An XML version of the SGML Open CALS Table model.
The OASIS Open XML Exchange Table model. This is an alternate table model for the XML version of DocBook.
An OASIS catalog for the DocBook XML DTD.
An OASIS XML Catalog for the DocBook XML DTD.
The recommended SGML declaration for the DocBook DTD.
The CVS ChangeLog for DocBook V4.2CR1.