I have volume 1 of Kim Il Sung’s works in English - printed in North Korea in the 70’s. I don’t know if the Foreign Languages Publishing House survived long enough for a Volume 2. They did put out some of Jong’s thoughts on film, if I recall correctly.
This is probably the prize of my collection. I have a first American printing of Lolita, which unfortunately has a bit of cat vomit stain on it or might be in that spot.
In terms for units sold I would guess that this is probably my rarest book.
After that I think these would be the rarest.
None of these are difficult to purchase but they are fairly specific to their topics.