A primary source gives you direct access to the subject of your research. Secondary sources provide second-hand information and commentary from other researchers. Examples include journal articles, reviews, and academic books. A secondary source describes, interprets, or synthesizes primary sources.
Can I reference a work that I wrote or created?
Yes. You mention the information you gathered and the techniques you employed in a scientific report regarding research you conducted. You might discuss earlier research you completed in a humanities article. You might talk about a piece of writing you've done in a literary analysis essay. Each time that happens, your written work would be a primary source.
Do primary and secondary sources require distinct citation styles?
No. How you format a source's citation is unaffected by whether it is primary or secondary for the subject you have addressed. How you structure your citations depends on the kind of work it is and the style manual you're using. MLA, APA, and Chicago are the three most used academic style manuals, and each has its own specific guidelines for citing just about any form of source, including images, websites, and YouTube videos.
Can a fictional piece be used as research for academic writing?
Yes. Any derivative works are considered secondary sources when examining a fictional work, whereas the original work itself serves as the primary source. However, if your writing is discussing how a particular event or subject is portrayed in fiction, you may use it as a secondary source. In general, fictional works are not acceptable sources for scientific or historical studies.