I have a question...if a book has writing on the inside cover (like a to and from) that is ok right?  And I would assume since former library books are ok if a book has an envelope thing (like a library book) glued inside the front cover that is ok too?  And since I recently saw a post here about stickers on books...is it ok for books to have price stickers on the outside of them?  Thanks!  Kim S

Yes that's ok. What you can't post is books that have notes and or highlighting in the text. But a inspcription or someones name on the cover or title page is ok.

Price stickers, store stickers, library stickers, bookcrossing stickers and remainder marks are also allowed as long as they aren't on a text page.