I'm writing a paper in APA-style. At the end of it, I have my references. There is this one paper (actually an internship report) that I refer to, but it hasn't been submitted for publication. How should I write this down?
Usually citations of gray literature should be avoided. If, however, it is necessary, the APA suggests to provide as much information as possible (see, for instance, the APA style blog). For specific style suggestions, see, for instance, a library handout summarizing the APA guides on gray literature.