Where Did the Gospel of John Get Its Stories?

In my previous two posts Ive talked about how John is very different from the other three Gospels, the Synoptics both in the stories it tells and the way it tells them.  That leads to the natural question.  Where did John (whoever the author was) get his stories from?   Its widely assumed he didnt make them all up and he certainly didnt make up the ones found in other Gospels, since they were written before him.   Then where did his stories come from?

Did Some of them the ones they have in...