Columbia subject headings:
Berlin Wall, Berlin, Germany, 1961-1989.
Germany (East)--Politics and government--1989-1990.
Harvard subject headings:
Berlin (Germany)--History--Chronology.
Berlin (Germany)--Politics and government--1990-
Berlin Wall, Berlin, Germany, 1961-1989
Germany--History--Unification, 1990--Chronology.
Princeton subject headings:
Berlin (Germany)--History--Chronology.
Berlin (Germany)--Politics and government--1990-
Berlin Wall, Berlin, Germany, 1961-1989.
Germany--History--Unification, 1990--Chronology.