Attributes: comparing two attribute values

If the bb/@id matches the  the link/@id then prepend the "right Link info"
to the contents of the bb element.
My problem is I'm not sure of the correct syntac for this test.
Any help would be appreciated.

<article>
<link id="bibT073213">right Link Info</link>
<link id="bibT073211">wrong Link Info</link>
............
<bb id="bibT073212">Mommy Reference Information</bb>
<bb id="bibT073213">Baby Reference Information</bb>
<bb id="bibT073214">Poppa Reference Information</bb>
</article>

Thanks