Augusto Monterroso

This is a long shot, I know, but would anyone have any idea on how to get in contact with Augusto Monterroso's estate? Among other things, he's noted for writing (at the time) the shortest short story ever called "The Dinosaur." Months ago I tried contacting Ediciones ERA, the publisher who most recently released his story collection Obras Completas (y otros cuentos) -- e-mailed them first in English (didn't hear anything) and then in Spanish (a friend helped translate) and still never heard anything. I'd really like to include his story in the anthology, and while anybody can simply find the story pretty much anywhere online, to print it I of course need permission, and I can only get that from his estate. On the off-chance anybody has information, please e-mail me at robert (at) robertswartwood (dot) com. Thanks!