cascading sort of 2 (or more) nodes

[gorgonz]

its no problem to do a simple sort of ONE node (author).
Just use <xsl:sort select=&quot;(node)&quot; ...>

I want to handle the situation, that there might be several entries (author) with the same node value. How can I tell a second sort condition to order those equal ones? criteria could be another node (title).

example database with first node author and second node title:

<books>
<book>
<author>Miller</author>
<title>Middle Book</title>
</book>
<book>
<author>Miller</author>
<title>Z, the last Book</title>
</book>
<book>
<author>Miller</author>
<title>A Starter Book</title>
</book>
</books>

thx in advance