Let’s start with the default option for citing an unpublished thesis or dissertation:
Author, A. A. (Year of publication). Title of dissertation or thesis [Unpublished doctoral thesis or master’s thesis]. Institution.
Here’s what that looks like in practice:
Nyet, D. (2005). Procrastination and dissertation completion times at three Ontario universities (Unpublished doctoral dissertation). University of Toronto.
Fleming, C. T. (1998). Valentine’s Day and the Macedonian horticultural industry (Publication No. 483294) [Master’s thesis, Saints Cyril and Methodius University]. ProQuest Dissertations and Theses Global.
When you’re not using a database, you may want to include a URL and/or archive name:
Obvius, C. (2014). The psychology of common sense (Doctoral dissertation, Donair University). Donair Institutional Repository. https://www.donair.edu/rep/157/thesis/
For more information about citing dissertations, please see pp. 333-34 of the Publication Manual of the American Psychological Association (7th ed.).