While the second link is of your father, it is the 1940 US Census and also shows his parents and brother, whom you don't have listed in your tree yet.
What is interesting to note is that your grandfather is listed in the 1940 US Census as being born in Illinois, as opposed to the Netherlands. This could be a clue for possibly finding more information. Even if Illinois is not where he was originally from, it could be where his parents were living at when he was young.