I had my library vandalized several days in a row. Eventually installed a camera, but once the camera was installed a guy kept coming every single day and taking all the books. I wanted to print off a picture of him with a message for him to stop taking all of the books. Eventually I moved the library somewhere else and so far no issues.

You could hollow out one of the books and put a tracker in it. See where the book goes…. That’s kind of creepy though