Columbia subject headings:
Christian union--History--Sources.
Ecumenical movement--History--Sources.
World Conference on Faith and Order--History--Sources.
World Council of Churches. Commission on Faith and Order--History--Sources.
Harvard subject headings:
Christian union--History--Sources.
Ecumenical movement--History--Sources.
World Conference on Faith and Order.
World Council of Churches. Assembly.
World Council of Churches. Commission on Faith and Order.
Princeton subject headings: