Abelujo can be used to register and sell second hand books.
If you only have second hands books: great, you have no restrictions.
However if you sell both new books and second hand ones, you can't, for now, register 2 different books with the same ISBN. You can't scan a new one and scan the same one but saying it's a second hand book.
The solution, as of today, is to create a generic "second hand USD 5" book card, and to sell this. You will see this line in the history of the day, instead of the book's title.
We plan to do this eventually but this isn't a priority. If you want to help finance the development, please contact us to join an effort with the other interested book sellers. Thank you.