ag.algebraic geometry - Are any two K3 surfaces over C diffeomorphic?

Let $S$ be a K3 surface over $mathbb{C}$, that is, $S$ is a simply connected compact smooth complex surface whose canonical bundle is trivial. I recall reading somewhere that any two such surfaces are diffeomorphic, however I can't for the life of me remember where, or how the proof goes.

Does anybody know a good reference to a proof, or can provide a proof?

Thanks,
Dan