When books are duplicated, the sources of the database range include book data in the paper duplication report. It has been explained that the database detection scope of paper duplicate checking includes books and book resources, but not all books are identified and covered by paper duplicate checking database. In the case of extended information, the source of the database scope includes the book data in the paper duplicate check report. It has been explained that the database detection scope of paper duplicate checking includes books and book resources, but not all books are identified and covered by paper duplicate checking database.