In University, I was part of a philosophy reading group where people would occasionally give talks about their on-going research. Several years ago I gave one such talk, and presented original and new ideas that were never published or presented in a more formal setting, although the ideas were also presented in a term paper I wrote that same year. There is no public record of the contents of the talk, or even that that talk happened.
Now I am in a situation where I wish to reference that same idea in a research paper. It is outside the scope of the current paper paper to present those ideas as a new thing, but it would be something that would be appropriate to reference as existing.
How would I do that? I could get a DOI for the talk and reference it using that, but I would feel weird about referencing an unavailable talk that I gave, as it would feel like citation padding. This is doubly true since it is early in my career. I could write up a summary of the talk and put it on a publicly available repository, but I’m not sure if that’s a thing that is done. Are there other options?