XSLT: how do I get to 3rd normal form with XLT?

Question

Here's an example XML file:

<?xml version="1.0" encoding="ISO-8859-1"?>
<!-- Edited by XMLSpy® -->
<catalog>
<cd>
    <title>Empire Burlesque</title>
    <artist>Bob Dylan</artist>
    <country>USA</country>
    <company>Columbia</company>
    <price>10.90</price>
    <year>1985</year>
</cd>
<cd>
    <title>Robbin in the Hood</title>
            <artist>Bradley Noel</artist>
    <artist>Gwen Stephany</artist>
    <country>USA</country>
    <company>Sublime</company>
    <price>Priceless</price>
    <year>1994</year>
</cd>
</catalog>

If I have some entries with multiple entries (for example, Artist: Bradley Noel, Gwen Stephany), how can I list them as two separate artists in my output? Should I nest a separate 'foreach' for records that may contain multiple values in a field type?

What I am actually having difficulty with is discovering a way to say "these artists belong to the same album".