

https://archive.org/details/heuvelmans-tras-la-pista
Just uploaded to Internet Archive the volumes of this extremely rare Spanish translation of On the track of Unknown animals by Heuvelmans.
As I said in my previous post, this edition from 1958 has very good an introduction written by Heuvelmans instead of Gerald Durrell. Also the chapter "There are lost worlds everywhere" has some paragraphs that were removed in the English translation, including a bit of Heuvelmans' opinion about UFOs. Personally, the covers are gorgeous.
If you have any rare Cryptozoological literature that is not online please consider digitizing it in the future, it doesn't matter the language.