DOCBOOK: how to... postscripize

I also tried to download "DocBook: The Definitive Guide" from 
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/docbook/defguide/en/

and from
http://www.oasis-open.org/committees/docbook/documentation/reference/fulltext.zip

how can I obtain a postscript file from these docbocs?

thganks and sorry for my english
-- 
Massimiliano Cialdi