He later received a Ph.D. in history from the University of Pennsylvania in 1953 after completing a doctoral dissertation titled "American Politics, 1795-1800." In 1961, he was awarded the Guggenheim Fellowship for the field of study of U.S. history.
He earned a Ph.D. in history from the University of Pennsylvania in 1953 and was awarded the Guggenheim Fellowship for U.S. history in 1961, both related to his research on American politics.