He was Secretary-General (1966–1970) and Honorary President (1990–1994) of the International Ornithological Committee.
ATP International Series | International Monetary Fund | International Red Cross and Red Crescent Movement | ATP International Series Gold | International Space Station | Advisory Committee on Antarctic Names | Amnesty International | International Olympic Committee | Committee of Public Safety | BirdLife International | UK Antarctic Place-Names Committee | International Finance Corporation | International Organization for Standardization | International Telecommunication Union | International Criminal Court | One Day International | International Nonproprietary Name | International Labour Organization | International Civil Aviation Organization | International Boxing Federation | Toronto International Film Festival | International Atomic Energy Agency | Republican National Committee | International Maritime Organization | International Development Association | John F. Kennedy International Airport | Central Committee | Los Angeles International Airport | International Bank for Reconstruction and Development | International Court of Justice |