That depends on whether you sell genuine books or not. If it's a genuine book with a legitimate source, that is, from a bookseller with wholesale and retail qualifications, then you can resell it without the authorization of the publishing house. The rights of the publishing house are exhausted after the first sale, and it is not illegal for others to buy and sell these books again. As for how to sell books, whether offline or online or live, as long as there is a legal source, it is not illegal. If the books you sell are pirated, that's another matter.