According to the APA style guide to electronic references (
,
366k), writers must include an article's DOI (Digital
Object Identifier) in citations if there is one for that
article.
Below is a brief guide to finding an article's DOI. More information on what DOI's are is available as well as all the changes to APA style as of July 2007.
There are a few ways to get the DOI for a piece of information.
1. Enter the citation information in CrossRef.
If you have a citation and/or list of references,
enter
the citation information here and the DOI will be retrieved.
2. From the article page in a database.
3. From the article page in a journal.

4. From the first page of an article.
