Defending the Papacy: Opposing the Sedevacantist Enterprise
You can do a search on the actual SSPX site as well.
Uh, what are you trying to prove? My understanding is that Fatima.org is a pro-SSPX site, and if you are look, there are articles defending the SSPX. When this author is talking about Sedevacantists, he's not talking about the SSPX.