 He was head of pure mathematics at the Mathematisch Centrum from 1960 to 1964, and dean of science at Amsterdam University from 1964 on.He also visited Purdue University (1959–1960), Washington University, St. Louis (1963–1964), the University of Florida (1966–1967 and winters thereafter), and the University of South Florida (1971–1972).He died on September 11, 1972 in Rotterdam.