[Death by Mirrors]

Uh, I don't think that would help. They're all translations and cheapo paperbacks, so it only shows the release date of the local version. No idea which one they had as a source. But now that you mention it, I do think the sixties version from my stack is a lot more innocent and tame than the eighties one. I always thought that was an attempt to draw younger readers towards Nancy Drew as well.