Hallstein, Walter, 1901-1982. United Europe: challenge and opportunity. Walter Hallstein - Cambridge: Harvard University Press, c1962. - 109 p. 21 cm. - The William L. Clayton lectures on international economic affairs and foreign policy, 1961-1962 . Subjects--Topical Terms: European federation. Historia Da EuropaUnion européenne. Dewey Class. No.: 940.5 / HAU 1962