Every once in a while, we get a question asking for a book or other educational reference on a particular topic at a particular level. This is a meta-question that collects all those links together. If you're looking for book recommendations, this is probably the place to start.
If you find a question that should be added to the list, edit it into the existing list answer rather than creating your own answer for it. See our policy on resource recommendations for details.
Related Meta: Do we need/want an overarching books question?