This one happens to have "Workshop track - ICLR 2018" at the top so has some dating, but most don't even have that
Papers without a date are usually preprints, or published independently (e.g. on the author's website) while expecting actual publication at some point.
https://www.biorxiv.org/content/biorxiv/early/2017/08/25/180...
I have been contemplating the relationship between random projections and compressive sensing since reading it and curious to read this paper for any insights on compressive sensing.