5.1.6 Electronic Source Information

The final element in a citation should identify the electronic format or online location of the source. For e-books, this may include a format such as PDF e-book, Kindle edition, or another platform-specific form. For online publications, provide a DOI or URL when applicable. Because DOIs are intended to provide a stable and persistent link to a work, they are preferred over URLs when both are available. For additional guidance on electronic source identifiers, consult CMS17, §14.4–7.

Access dates are generally unnecessary and should not be included unless required by the publisher or essential to the nature of the source.

If URLs are used, do not hyphenate them at line endings. When a URL must break across lines, divide it before a period or at a slash.