A Digital Object Identifier (DOI) is a number assigned to a research article that will always be used to identify where that resource is located online.
This example APA citation includes the DOI number at the end of the citation (highlighted):
Holmqvist, M., Button, P., & Heath, O. (2019). Together we stand: The imperative for interprofessional education in professional psychology training. Canadian Psychology/Psychologie Canadienne, 60(4), 255–264. https://doi-org.tu.opal-libraries.org/10.1037/cap0000180
A DOI is composed of the following elements:
Some additional information about DOIs...