It didn't work, but that could actually be my fault, as the code I put in the first post was a simplified example and is not exactly the same. I'll put an actual extract:
Code:
<h2 id="sigil_toc_id_1">CAPITOLO I.</h2>
<h3 id="sigil_toc_id_2">Come Candido è allevato in un bel castello e come n'è cacciato via.</h3>
Edit: To be more precise, your code found no matches