Digital Object Identifiers
Scholarly publishers are assigning a unique Digital Object Identifier (DOI) to individual articles and documents. Include the DOI in your citation; see page 7, example #1 in the APA Style Guide to Electronic References.
DOI prominently displayed at the beginning or end of the article:
Sometimes the DOI can be found on the database screen:
Do not use any set of numbers – it MUST start with DOI:
You can also use CrossRef to look up DOI numbers:
Using the lookup feature in CrossRef, try author and title:
The DOI is displayed – copy and paste to your citation: