Once i was looking for a paper, to construct a list of interesting sources for a professor I was working for. It was a paper on a very relevant topic that woul

Once i was looking for a paper, to construct a list of interesting sources for a professor I was working for. It was a paper on a very relevant topic that would really be of interest. It had been cited in a dozen different papers, or so. But I could not find the cited paper anywhere! I realized I could find the author of the cited paper, and just email them. They said "Oh, that was a conference presentation, it was never published as a paper anywhere, only presented orally at the conference." Fine. Except... most of these citations didn't cite it as a conference presentation. Most of the citers, I am pretty sure were not at that conference. They just copy and pasted the citation from other papers, thinking the same as me, oh, that seems a useful cite. The first couple times it was cited, it might have actually been cited as a conference presentation at a particular conference on a particular date, but that wound up omitted from future copy pastes. I don't think this was a particularly unusual occurence. Many citations are... unreliable. A citation to something with an actual URL is pretty good.