The OWL resources will help you learn how to use the American Psychological Association (APA) citation and format style.

Some database articles may include a DOI, a Digital Object Identifier, a unique number that is assigned to an entity that is available on a digital network. The DOI allows networks to keep track of objects such as electronic journal articles, even when the objects are moved from one Internet location to another.  

DOIs are commonly assigned to research articles.  That is, most articles in newspapers, magazines, and trade journals will not have a DOI. When an article contains a DOI, APA style allows for the inclusion of the DOI at the end of your citation. See example of an APA citation that uses a DOI:

Ramstetter, C., Murray, R., & Garner, A. (2010). The Crucial role of recess in schools. Journal
     of School Health, 80(11), 517-526. doi:10.1111/j.1746-1561.2010.00537.x.

Do I need to include a DOI on my reference?

See the DOI Flowchart (PDF) (APA Website)

Citing articles without a DOI in your reference list

According to the APA Manual (6th Ed.), when there is no DOI, "provide the home page URL of the journal or of the book or report publisher."  (p. 191, APA Manual).

Periodicals - Article in a subscription database with no DOI (library database):

Holt, N., Tamminen, K., Black, D., Mandigo, J., & Fox, K. (2009). Youth sport
      parenting styles and practices. Journal of Sport & Exercise Psychology, 31
      (1), 37-59. Retrieved from http://journals.humankinetics.com/jsep

Nasu, L., Shamah, T., & Rivera Dommarco, J. (2007). Prevalence of overweight
      and obesity increase in teenager Mexican women. FASEB Journal, 21(5),
      A672. Retrieved from http://www.fasebj.org/

Periodicals - Article freely available online with no DOI:

Pierce, L., Steiner, V., Seymour, J., Wicks, B., Wright, C. & Thompson, T. (2010).
     Questions caregivers asked in caring for persons with stroke.   Online Journal
     of Nursing Informatics (OJNI), 14(2). Retrieved from http://ojni.org/14_2/Pierce.pdf

Have a DOI and need to find out the article?

Type or paste a DOI name (e.g., 10.1000/182) into the text box below.

Have the citation and need to find out its DOI?

Go to the CrossRef Simple Text Query page, paste your reference in the box provided and click on "Submit" to obtain the DOIs, when available. Note: Some articles don't have a DOI.