Oecd Member Countries -- See OECD countries Here are entered works on the member countries of the Organisation for Economic Co-operation and Development. Works on the OECD as an international body are entered under Organisation for Economic Co-operation and Development.
Oecology -- See Ecology Here are entered works on the interrelationships of organisms and their environment, including other organisms. Works on the composite of physical, biological, and social sciences concerned with the conditions of the environment and their effects are entered under Environmental sciences. Works on the relationship of humans to the natural environment are entered under Human ecology. Works on the relationship of humans to their sociocultural environment are entered under Social ecology. --subdivision Environmental aspects under subjects, e.g. Agricultural chemicals--Environmental aspects; Nuclear power plants--Environmental aspects; and headings beginning with the word Ecological
Oecumenical Movement -- See Ecumenical movement Here are entered works on a movement for the purpose of church cooperation and unity, generally dated from the Edinburgh Missionary Conference of 1910 and leading to the formation of the World Council of Churches in 1948. Works on prospective and actual mergers within and across denominational lines are entered under Christian union. Works on unity as one of the "marks" of the church are entered under Church--Unity. Works on religious activities planned and conducted cooperatively by two or more Christian sects are entered under Interdenominational cooperation.