I found this collection of stories on a Spanish language website while following up a lead from the Fairy Investigation Society. It was written in 2003 by a Sr Fabio Picasso, and was a Spanish version of an article in French (presumably by the same author) called "Les petits êtres d'Argentine" ["The little beings of Argentina"] originally published in La Gazette Fortéenne ["The Fortean Gazette"] volume II, Oeil du Sphinx, París, 2003, and he linked it to a website which is no longer active. For myself, I have used Google Translator as a basis, but have made changes when necessary for greater accuracy and readability. I have also transferred his endnotes into the main text for the sake of readability. With this in mind, welcome to a series of strange encounters. I have translated duende as "goblin", but it is a catchall term for goblins, elves, etc. - even ghosts. I draw no conclusions about the nature of the phenomena described, except to say that, whereas a single witness may be discounted, it is a lot harder for multiple witnesses.
