If you order 2 books from my shelf with credits, you may select 2 additional books for free (a 4 books for 2 credit deal). Just make sure you send me a PM with what you want as your free selections. I am open to other deals, generally based on total weight of the package, so feel free to ask. Our home is smoke free and we have no pets, however, most of my books are from outside sources so I do not know their history.