A DOI (Digital Object Identifier) is a series of numbers used to identify ebooks and journal articles. Many online resources will possess their own unique DOI. The DOI of an eBook can often be found on the details page of the resource or on the front page of an article. If you can't find the DOI use the following free online tool to look it up: https://search.crossref.org/
Download Crossref Guide
DOIs must take the format https://doi.org/xxxxx (do not add a full stop after it, e.g. https://doi.org/10.12964/jsst.19005)
Please note that some sites use dashes to formulate the DOI. It is okay to use this format providing the link works e.g. https://doi-org/xxxxx
If available, always add a DOI to the end of print or online resources in your reference lists.
Always add DOIs to sources from academic databases. Never use URLs for these resources.
URL (Uniform Resource Locator) is a reference (an address) to a resource on the Internet. Urls should link directly to the source being cited and can be found in the address bar of your internet browser.
For websites (not including academic research databases), which don't have DOIs, provide a URL in the reference.
If a URL is broken, do not include it in the reference. Copy and paste live URLs to references (do not add a full stop after them).
Section 9.35 of the APA Publication Manual states that is acceptable to use either the default display setting (blue hyperlinks) or plain text (without underlining) when formatting DOIs and URLs in reference lists. However, it also recommends that these links should be live if the sources being cited are published online.
ACAP recommends the use of live, blue hyperlinks in reference lists. Remember to be consistent throughout the entire document.
See also the APA Style and Grammar Guidelines for more information.