I brought it up as an appeal to common knowledge. Schraf confirmed that it is common knowledge. You are the one who said you'd studied it in great depth, not I, so you are the one in a position to supply the evidence.
Since it came up I'm now curious about it. I did a little googling on the subject but there's nothing scholarly out there that I could find in such a brief foray, though there are references to the fact that all cultures have versions of this, so it's not just an individual quirk or isolated to some parts of the world.
Interesting though that fairies and gnomes and UFOs are classified by some as intermediate between the angelic orders and humanity. There was a Reverend Kirk of Scotland who was obsessed with the fairies and wrote a book on the subject:
Parascope.com
This is all pretty off topic though. I was assuming any such phenomena are fallen angels, which I know exist, but this is all something else.
Anyway, I look forward to your bibliography which must be quite extensive to judge by the depth to which you claim to have studied these things.