I don't think 'rare' is the right word here. Rare means you can't find it easily, not 'what you have missed or don't know about'. But then what is the word for that? English doesn't have it, afaik. Perhaps 'unexplored treasures'?
Like so: "Less-known treasures you probably haven't read" but this doesn't have a zing to it.
Or? "A collection of useful tech books you've probably missed" sounds more accurate, though not sensational.
Like so: "Less-known treasures you probably haven't read" but this doesn't have a zing to it.
Or? "A collection of useful tech books you've probably missed" sounds more accurate, though not sensational.