A few originals by Heinrich Kley, offered at various auctions. The last image recently at Heritage. If I had my pick, I'd choose the first one, it looks like a master animation drawing. So effortlessly scribbled down. As I pointed out earlier, the Disney animators didn't have such knowledge of anatomy when working on the centaurs for Fantasia's Pastoral sequence.
Today Kley's work is still the standard when it comes to depicting fantasy characters with realism.