Art books?

My wife was using E-Hentai to find art books for various manga and anime, weird place but I guess. E-Hentai just deleted itself from her sources and we can't figure out how to bring it back.

Strange thing is she can click the link to the source and it brings her there just fine. I have tried to reinstall the extension but I couldn't find it. Anyone have some advice for us?

Edit: The source not the extension