I have never heard of that Textbook Torrents site before. While they don't provide a link, given the name, it's easy to Google for it.
Interesting current note on their page:
On Friday, we received a request from Pearson Education, one of the bigger textbook publishers, listing 78 torrents that they wanted disabled. While they are acting on extremely shaky legal ground, we are not in a position to fight a legal battle with the organization. As a result, in the interest of allowing the continued existence of this place, I have acceded to their request and disabled access to the listed torrents. Because of the batch process I used, uploaders will not receive the usual notification associated with a disabled torrent.
This is not a happy day, but I want to take the opportunity to make a few comments. First, I swear to you that I will do everything in my power to prevent the server's logs from falling into the hands of those that might use them against you. If that means bankrupting myself in the process, so be it. I would prefer that it not come to that, but I have drawn a line which I will not cross no matter the cost.