[xsl] Quotes within Quotes within Quotes

Alright, Having quotes within quotes is a common thing but what's about
this:

<xsl:attribute
name="{concat('xmlns:schemaLocation='http://www.test.com/bta ','$path',
'PS_ReportRequest.xsd'')}"/>


Well the first " " is clear.
The next ' is there to distinguish between the strings.
However we would need to have a single ' in the first string and last
string.  How do I escape those?


Any idea?

Thanks
Houman