In all honesty, I have no clue how to use a regex... But here's the a href in the doc... And it just repeats a couple of times throughout the book.
<a href="../OEBPS/Note.xhtml">Note</a>
The document it's linking to is part of the ePub, and it is titled "Note.xhtml"
Like I said though - the links work perfectly fine except in iBooks.