A DOI (Digital Object Identifier) is a standardized unique number given to some articles, papers, and books, by some publishers, to identify a particular publication. Not all publications have a DOI number. If you cannot locate a DOI for a source you want to cite, use the URL of the homepage of the journal itself (not the link to the specific article) or the URL of the book or report publisher.
If you have a reference and can't find the DOI number, or have a DOI number and are missing the reference, try using the Crossref Free DOI Lookup
DOI format: https://doi.org/xxxxx
Example DOI
Example URL
Guidelines for using DOIs or URLs
- If a DOI is present, use the DOI instead of the URL.
- Do not use "Retrieved from" or “Accessed from” before a DOI or URL.
- If a work does not have a DOI and is from a research database, do not include a URL or database information. Treat the reference the same as if for a print version of the work.
- If a work comes from a database that publishes original or proprietary material that is only available in that database or for works in databases that have limited circulation, use the name of the database or archive and the URL of the work cited. However, if the URL requires a login to access it, instead use the URL for the database or archive home page or login page instead of the URL for the work.
Database Information in References
- For most references, do not include retrieval dates. However, if the work is not archived and will be updated or may change over time, then include a retrieval date.
When to use Retrieval Dates
- Copy and paste the DOI or URL directly from the web browser into your reference list.
- Do not insert a hyphen if URL or DOI will extend into next line. Break before the punctuation
- Do not add a period after a DOI or URL.
- Do not enclose the URL/DOI in brackets.
When to Include DOIs and URLs & the Format of DOIs and URLs:
DOIs and URLs
If a DOI or URL is really long, you can use shortDOIs or shortened URLs:
DOI and URL Shorteners
Learn more about how the Source element is formatted in a reference list entry
Reference Examples
