What do I do if I can't find a DOI for a reference entry?
Not every article has a DOI. If you've made an effort to see if it has one and couldn't find it, then it's fine that you don't include it in the reference entry. You can't include something it doesn't have.
In general when looking for DOIs, you can check:
- the PDF of the article itself
- the article's record in the database it was found it in, such as PsycINFO or Academic Search Complete
- the the article's record on the journal's website
- Searching the title in the metadata tab of Crossref.org
If it can't find it in any of those places, then there probably isn't a DOI to be found. If you're still not sure or want to double check, you can ask a librarian for help.