How do I know which book I'm hunting?
This does not mean that all of those books are still there. If the location is a book-swap shelf, Little Free Library, or something similar, there may be lots of books on hand, but if it's a public place like a park bench or a bus stop, it's unlikely that any of the older releases are still there.
If you click on an individual book and scroll down to see its release notes, you may learn more about where and when it was released. Sometimes people post photographs showing the specific spot. But not everyone provides a lot of detail, and even if they do, the book may have been taken already. But sometimes people take books and then bring them back to the same spot, so you never know what you might find if you stop by to look!
Hope this helps!