What Does Nabokov Look Like?

I've been reading a book on Nabokov, and I've noticed something: I have no idea what he looks like.  I wouldn't know him if I bumped into him on the street; not likely, I know, but imagine someone who admired Mark Twain, say, who if asked to describe him said, "Well, uh, I'm pretty sure he had a moustache."  Maybe it's just me, but look at these pictures and see if they don't all seem to be different people.  I mean, I know he's a bald white man, but is it really the same bald white man?  Hell, I'm a bald white man.  Maybe I'm Nabokov.