Keep in mind that you will probably not find a DOI numbers for every article. The DOI system started in 2000 and not all publishers register their content in the DOI system. Participation is increasing, so the more recent the article, the more likely you will find a DOI.
Some of our journal databases will show the DOI number if there is one available. Academic Search Premier, for example, gives the DOI along with the description of the article. Here is a screenshot that shows where this will typically appear:
Some databases might not have this in the description, but a DOI might be on the PDF of the actual article. This is sometimes the case in the JSTOR database.
If a DOI is not available, then use the “permalink’ or “stable URL” that the database generates. Here is how it looks in Academic Search Premier:
Permalinks will not be as reliable as a DOI in the long run, which is why both MLA and APA citation forms now favor DOI numbers. (Note that when accessing a ‘permalink’ from off campus, you will need to enter a library card number to open the link.)