Finding and pasting an ISBN
An ISBN (International Standard Book Number) identifies one edition of a book. Books published since 2007 carry a 13-digit ISBN that starts with 978 or 979; older books may show a 10-digit ISBN. Look on the back cover above the barcode, or on the copyright page. You can paste it with or without hyphens and spaces.
The last digit is a check digit. The generator verifies it before any lookup, so a mistyped ISBN is caught immediately with a clear message instead of returning the wrong book.
Where the book details come from
Your browser asks the Open Library Books API for the ISBN, and if that has no record, Open Library search. Open Library is an open catalogue run by the Internet Archive. It covers many books well, but some records lack a city, an edition statement or a subtitle. The form shows all fields so you can complete them from the book in your hands.
Sapolsky, R. M. (2017). Behave: The biology of humans at our best and worst. Penguin Books.
In-text citation: (Sapolsky, 2017)
Gleick, James. Chaos: Making a New Science. Penguin, 1987.
In-text citation: (Gleick)
Edition, year and publisher: what to check
- Edition: cite the edition you read. "2nd ed." in APA, "2nd edn." in Harvard.
- Year: use the year of that edition, not of a later reprint.
- Publisher: APA 7 and Chicago 18 omit the place of publication; Chicago 17 and IEEE include it.
- Authors and editors: an edited book lists editors, and a chapter in it needs the book chapter form.
If you cite one chapter of an edited book, choose Book chapter in the manual form and add the chapter author, chapter title and page range. The reference generator page explains reference lists in more detail.
E-books and books without an ISBN
E-books often have their own ISBN; cite the version you read. If an e-book has a DOI, the DOI citation generator usually gives richer data. Older or local books without an ISBN can be entered in the manual form with author, title, year, edition and publisher.
ISBN-10 and ISBN-13 are the same book
An ISBN-10 can be converted to an ISBN-13 by adding 978 in front and recalculating the check digit. The generator handles both, so paste whichever you have. Different formats of the same title, such as hardback, paperback and e-book, have different ISBNs; use the one for the format you read, because page numbers can differ.
Translated books need the translator in many styles. Add the translator in the manual form if Open Library did not list one.
Finding an ISBN in a library catalogue
If the book is not in front of you, search your university library catalogue or Open Library for the title. The record usually lists one or more ISBNs; pick the one for the edition you used. Library records also show the edition statement and publisher, which helps you check what the lookup returned.