Link to other sections of the manual or to external sources instead of recreating documentation.
Linking to other sections of the manual may be done using the <link> tag (to which you must provide link text).
<para>
"Link" links to a section, using descriptive text: <link
linkend="doc-standard.recommendations.links">documentation on
links</link>.
</para>
To link to an external resource, use <ulink>:
<para>
The <ulink url="http://framework.zend.com/">Zend Framework site</ulink>.
</para>