There are a couple places to find a DOI number:

1. With the article information in a database

2. Look on the PDF of the article itself. It is usually placed at the top or bottom of the page, in what would be the header or footer.

If you are unable to find a DOI number in the database or on the article, use a permanent URL that will take your reader to the source in the database or website.

In ProQuest databases, go the Abstract/Details tab and scroll down to find the "Document URL"

In Gale databases, click on the "Get Link" button in the top menu.

In JSTOR, look for the stable URL in the left hand column next to the article or book chapter.

In EBSCOHost databases, click the "Permalink" tool in the right hand menu and a permanent link will be created for you.

In ScienceDirect, Sage Journals, Taylor & Francis, ProQuest eBook Central, and Springer Link, use the URL at the top of the web browser.

When citing sources, DOI is preferred according to citation manuals as those using these manuals are often publishing for the wider community of researchers and a DOI will allow everyone to find the source again, no matter what institution they work at.

If they input the DOI into a web browser's search they will be taken to the page on the publisher's website about the source.

There is one issue when it comes to doing that for college research, the library may not have access to the source through the publisher's website.

So it's probably better to provide a permanent link to the source that will enable your professor to get access to the full text.

Consult your professor for their preference about URL vs. DOI to be sure.