Harvard University | Columbia University | Yale University | University of Paris | New York University | Stanford University | Princeton University | University of Cambridge | University of Pennsylvania | University of Michigan | University of Chicago | University of California, Berkeley | University of Toronto | Cornell University | University of Oxford | University of London | University of Oslo | Cambridge University | University of Southern California | McGill University | Johns Hopkins University | Northwestern University | University of California | Brown University | University of Queensland | University of Minnesota | University of Washington | University of Notre Dame | University College London | Duke University |
He held a number of Visiting Professorships: University of Rochester, USA, 1958–1959; Kiel University, University of Osnabrück, 1977; University of Baroda, Jadavpur University, 1978; University of Ottawa, 1981.