First of all, all the books in the library have their own bar codes, so you won't worry about your books being mixed with the library's own books. However, as a public place, if you bring books in and out at will, it may bring inconvenience to staff management. Moreover, the purpose of everyone going to the library is to look up books that they don't have. Why did the subject choose to bring his own books to the library instead of the study room?