APA Style uses a hanging indent format for references. Each Reference list entry should begin flush to the left margin, with second and subsequent lines indented between five and seven spaces (around a half inch or 13 mm). APA Style requires double spacing of references when preparing a manuscript to submit for publication. However, students preparing to submit an electronic thesis or dissertation should review the “General form and style” suggestions on spacing provided by the College of Graduate Studies and Research. If reference list entries in a thesis are single spaced, double spacing (or 1 ½ line spacing) should still be used between each entry.
Examples provided in this guide are arranged under the heading supplied in the Publication manual (6th ed.). If needed, refer to Chapter 7 of the manual which contains a wider range of reference examples. Appropriate examples can be located using the volume index or the chapter contents index (pp. 193-198). Also note the procedure for referencing a work not covered by a specific example:
choose the example that is most like your source, and follow that format. . . . When in doubt, provide more information rather than less. . . . most entries contain the following elements: author, year of publication, title, and publishing or retrieval data—all the information necessary for unique identification and library search. (p. 193)
See also APA 6.31 (pp. 187-192) for general discussion of electronic resources.
What is a DOI?
A DOI (digital object identifier) is a unique alphanumeric string assigned to a specific electronic resource which provides a persistent link to its location.
ex: doi: 10.1037/0278-6126.96.36.1999
When available, include the DOI in your journal article references.
See pages 187-192 & 198-199 of the APA Publication Manual for more information
Where Can I Find the DOI?
Most databases include a DOI (if available) in the full record. For example, in PsycINFO, choose the Complete Reference link to see if a DOI is listed. DOIs can also be identified on the article's itself and/or on the publisher's website where the articled resides.
As indicated in the Publication Manual of the American Psychological Association (pg 198):
"If no DOI is assigned to the content and you retrieved it online, include the home page URL for the journal, newsletter, or magazine in the reference. Use this format: Retrieved from http://www.xxxxxxxx"