As mentioned above, the DOI is available mainly for scholarly journals. That means that a database that includes magazines or reference books as well as scholarly (peer-reviewed) journals may have some articles with DOI and some without.
The DOI is sometimes given as part of the text of an article, above or below the abstract. See also under PDF files, below.
Many, but not all, Gale databases give a DOI where one is available. Click the title of the article to display the abstract/full text page. The information about the article may include a DOI. If a PDF version of the article is available, the PDF may contain a DOI. If the form is
Remove the http://dx.doi.org/ and substitute doi:
Click on the title of the article to display the full text. The DOI is shown at the top of the Article tab, above the title of the article.
Some journals print a DOI for each article, usually at the top or bottom of the first page of the article, or near the abstract.
If there is a periodical article without a DOI, the MLA style requires you to give the URL after the database name.