Columbia subject headings:
Northern Ireland--History--1968-1998.
Northern Ireland--History--1998-
Harvard subject headings:
Northern Ireland--History--1968-1998.
Northern Ireland--History--1998-.
Political violence--Northern Ireland--History--20th century
Social conflict--Northern Ireland--History--20th century.
Princeton subject headings:
Northern Ireland--History--1968-1998.
Northern Ireland--History--1998-