Whether through your personal electronic device or computer, OPAC (Online Public Access Catalog) lists the holdings of the Charlotte, Canadian and Australian Libraries of the Living Church of God, by subject, title, author or ISBN. A unique ISBN (International Standard Book Number) is given to each book edition and variations such as paperback, hardcover or e-book, but not reprintings. An ISBN varies from country to country depending on the size of the country’s publishing industry. A book may not have an ISBN if it is privately published or the author doesn’t follow the normal ISBN procedure. Magazines, on the other hand, are identified by International Standard Serial Numbers (ISSN).