Why do we need different bibliographic entries for two books with the same author and title? Because one may be the first edition, and the other may contain rewritten sections, new pictures, updated figures, a new translation, or new introductions. A bibliography needs to reflect what you have actually read, not just a vague concept of the book.
Start by comparing the two editions. Do not begin reading until you have examined the title pages and copyright pages. Write down the edition, publisher, date, ISBN, editors or translators, and any other subtitle. You will likely find that even though the two covers look very similar, the edition information was created differently. The edition information is usually easy to find but may not always be in big type. Look for phrases like “second edition,” “revised edition,” “expanded edition,” or “new edition.”
Sometimes the edition information is not an exact reflection of the content; a second or revised edition could be entirely different from the first, but a later printing may not be. Phrases like “third printing” or “paperback reprint” are not necessarily second or revised editions.
Dates may be confusing, too. On the copyright page, there may be multiple years connected to the work, including the original date, the date of revision or translation, and the date of the copyright renewal. The most recent date listed on the copyright page may not be the publication date of the version you are citing. Make sure the date matches the edition, publisher, and ISBN.
Sometimes the library catalog will give you the right information, but you should check this against your actual version of the book because the catalog may list a different edition. Sometimes there will be a new editor, translator, commentator, or organization involved in the edition you are holding. This may have an impact on your citation as well as how the content of the book has changed.
If you are citing a quote, paragraph, or specific section of the book, be sure you have the right edition. Another edition of the book may present the quote or passage on a different page or with different wording.
Be sure to keep each edition in its own source entry. Don’t overwrite the previous edition with the new edition. Each entry needs its own publication information, ISBN, page numbers, and a description of the edition used. Otherwise, the bibliography will look like it has duplicate entries that should really be combined, when in fact they are not.
Edition information isn’t just decoration for a citation. It provides information to a reader about the specific text, layout, translation, and page numbering that were used to write your essay. If you are citing two copies of the same book, it may be the difference between a revised edition statement and a unique ISBN that makes all the difference.
