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.
Click the title of the article to display the abstract/full text page. The information about the article, following its title, may include a DOI. If the publisher's PDF version of the article is available, the PDF may contain a DOI.
Click on the title of the article to display the full text. The DOI is shown above the abstract, after the Cite menu.
In Education Full Text he DOI is given in the brief description on the results page, after the page numbers. In the full records of both Education Full Text and CINAHL, it is one of the labeled areas following the abstract.
If available, the DOI appears in the PDF.
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.