In my career I have cited many non-peer-reviewed sources within my academic papers. Off the top of my head this has included:
- Government reports
- NGO reports
- Longitudinal studies
- Newspaper items
- Magazine articles
- Television programs
- Personal communications
I am aware of at least one journal that suggests that "personal communications" should be formatted in the reference list just like any other reference, instead of the usual parenthetical comment.
It is much, much less common now but it was not that long ago that I would run into a citation of a meeting abstract with some frequency.
The entire point of citation in a scientific paper is to guide the reader to an item from which they can draw their own conclusions and satisfy their own curiosity. One expects, without having to spell it out each and every time, that a citation of a show on ABC has a certain quality to it that is readily interpreted by the reader. Interpreted as different from a primary research report or a news item in the Washington Post.
Many fellow scientists also make a big deal out of their ability to suss out the quality of primary research reports merely by the place in which it was published. Maybe even by the lab that published it.
Despite all of this, I have seen more than one reviewer objection to citing a preprint item that has been published in bioRxiv.
As if it is somehow misleading the reader.
How can all these above mentioned things be true, be such an expectation of reader engagement that we barely even mention it but whooooOOOAAAA!
All of a sudden the citation of a preprint is somehow unbelievably confusing to the reader and shouldn't be allowed.
I really love* the illogical minds of scientists at times.