Fairies - real fairies, that is

Today, I was asked to find books about Fairies.  Not "fairy tales", but about real fairies.  Aside from my own personal disbelief that fairies actually exist (while I do believe in ghosts, and I have a few library ghost stories to share later, fairies are not on my list of 'mythical creatures that actually exist but are simply hiding from us lunkers'), I was able to find about a dozen books in the system that were in the non-fiction section that concerned fairies, including the Time-Life series "the Enchanted World", specifically the one about Faires and Elves.  Which I also have in my private collection (and I did admit that to the patron, although I also told her that I didn't think it would help).