An ISBN is assigned to each edition and variation (except reprintings) of a book. For example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, and 10 digits long if assigned before 2007.
Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure; however, this can be rectified later.
As a service to the Caltech community, the Caltech Library provides ISBNs for self-published materials.
If you are interested in obtaining an ISBN for your self-published book, please contact the Library.
Before requesting an ISBN for your book, please gather the following information. The library will ask you to include it in an email.