Ask the Library: Reference

APA  discusses two types of unpublished manuscripts: (1) Unpublished and (2) Informally published

Unpublished means that the manuscript is only in the possession of the author. In this case the basic form looks like:

Author. (year). Title of the work. Unpublished manuscript. Department Name, University Name. 

Informally Published means that, although the work hasn't been formally published, it's been posted online. In this case the basic form would look like:

Author. (year). Title of the work. Unpublished manuscript. Department Name, University Name. DOI or URL

APA 7th manual Section 10.8 Unpublished Works and Informally Published Works