We had a discussion about this in a different thread a while ago. I have Dodger team items with Zimmer signatures from 1955 that show he used a closed "D" then, but by 1959 he had apparently switched to the open "D". I am positive all of these below are authentic Don, not the wife. It may account for why PSA authenticates them sometimes. Player signature styles can vary over their lifetimes.
zimmer autos.jpg