What is a DOI?

A DOI, or digital object identifier, is a unique alphanumeric string assigned to an online document such as a journal article or ebook. A DOI can be used in a similar way to a URL, but it is more permanent and reliable.

Because a DOI never changes, academic citation styles recommend using DOIs instead of URLs to locate sources when possible.

DOIs can be formatted in various ways:

  • doi:10.1080/02626667.2018.1560449
  • https://doi.org/10.1080/02626667.2018.1560449
  • https://dx.doi.org/10.1080/02626667.2018.1560449

How to find a DOI

The DOI will usually be clearly visible when you open a journal article on a database.

Examples of where to find DOIs


*Note that JSTOR uses a different format, but their “stable URL” functions the same as a DOI.

What to do when you cannot find the DOI

If you cannot find the DOI for a journal article, you can also check Crossref. Simply paste the relevant information into the “Search Metadata” box to find the DOI. If the DOI does not exist here, the article most likely does not have one; in this case, use a URL instead.

Crossref arrow

Using DOIs in citations

You may need to use DOIs when citing online journal articles or certain books. Follow the standard rules for citing that type of source in your citation style, and place the DOI in the space where the URL would usually go.

APA citation with DOI

G, M. O., Grigsby, J., Poulter, B., Van Derveer, J. W., Giron, S. G., Jerome, L., … Doblin, R. (2018). 3,4-Methylenedioxymethamphetamine-assisted psychotherapy for treatment of chronic posttraumatic stress disorder: A randomized phase 2 controlled trial. Journal of Psychopharmacology, 32(12), 1295–1307. https://doi.org/10.1177/0269881118806297

In APA, you may use the following DOI formats:

  • https://doi.org/10.1177/0269881118806297 (recommended)
  • http://dx.doi.org/10.1177/0269881118806297
  • doi:10.1177/0269881118806297.

You can use Scribbr’s free citation generator to easily cite journal articles using the DOI. All relevant information is automatically retrieved and correctly formatted according to the citation style.

Scribbr APA Citation Generator

MLA citation with DOI

G, Marcela Ot’alora, et al. “3,4-Methylenedioxymethamphetamine-Assisted Psychotherapy for Treatment of Chronic Posttraumatic Stress Disorder: A Randomized Phase 2 Controlled Trial.” Journal of Psychopharmacology, vol. 32, no. 12, Dec. 2018, pp. 1295–1307, doi:10.1177/0269881118806297.

MLA recommends using the format doi:10.1177/0269881118806297.

Scribbr MLA Citation Generator

Chicago citation with DOI

Nair, Lakshmi S. and Cato T. Laurencin. “Biodegradable polymers as biomaterials.” Progress in polymer science 32, no. 8-9 (2007): 762-798. https://doi.org/10.1016/j.progpolymsci.2007.05.017.

In Chicago style, the format https://doi.org/10.1177/0269881118806297 is preferred.

What can proofreading do for your paper?

Scribbr editors not only correct grammar and spelling mistakes, but also strengthen your writing by making sure your paper is free of vague language, redundant words and awkward phrasing.

See editing example

Frequently asked questions about DOIs

Why are DOIs important?

A DOI is a unique identifier for a digital document. DOIs are important in academic citation because they are more permanent than URLs, ensuring that your reader can reliably locate the source.

Journal articles and ebooks can often be found on multiple different websites and databases. The URL of the page where an article is hosted can be changed or removed over time, but a DOI is linked to the specific document and never changes.

How do I find the DOI of an article?

The DOI is usually clearly visible when you open a journal article on an academic database. It is often listed near the publication date, and includes “doi.org” or “DOI:”. If the database has a “cite this article” button, this should also produce a citation with the DOI included.

If you can’t find the DOI, you can search on Crossref using information like the author, the article title, and the journal name.

How do I format a DOI in APA style?

In your reference list entry for a journal article or other online source, APA currently recommends writing the full DOI address that gives access to the article. For example:


The old guidelines were to present DOIs by writing “doi:” followed by the numerical string. For example:


If you’re following the 6th edition, this format is still accepted, as long as it’s used consistently.

When should I include a DOI or URL in an APA journal citation?

In an APA journal citation, if a DOI (digital object identifier) is available for an article, always include it.

If an article has no DOI, and you accessed it through a database or in print, just omit the DOI.

If an article has no DOI, and you accessed it through a website other than a database (for example, the journal’s own website), include a URL linking to the article.

How do I format a DOI in MLA style?

In MLA style citations, format DOIs with the prefix doi: followed by the string of letters and numbers.


DOIs are used mainly when citing journal articles in MLA.

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Courtney Gahan

Courtney has a Bachelor in Communication and a Master in Editing and Publishing. She has worked as a freelance writer and editor since 2013, and joined the Scribbr team as an editor in June 2017. She loves helping students and academics all over the world improve their writing (and learning about their research while doing so!).

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