Can I retrieve node-set from the document using a var

Hi,
I am wondering whether this is possible at all.
I have a variable initialized with a node set retrieved using document
function like below
<xsl:variable name="emps" select="document( './production.xml')"/>
I also have another variable let's call it "ref" that I return from the
template by using call-template function that return to me a path string
like this: "/path1/path2/path3".
I would like to use this string to retrieve a node-set from my variable that
keeps the document, something like this:
	$emps[$ref]
Is there any way to perform this or do this some other way?
Regards,
Janusz