Columbia subject headings:
Harvard subject headings:
Border crossing--Political aspects--Germany--History.
Germany (East)--Boundaries--Germany (West)
Germany (East)--Politics and government--1989-1990
Germany (West)--Boundaries--Germany (East)
Germany--History--Unification, 1990
Princeton subject headings:
Border crossing--Political aspects--Germany--History.
Germany (East)--Boundaries--Germany (West)
Germany (East)--Politics and government--1989-1990.
Germany (West)--Boundaries--Germany (East)
Germany--History--Unification, 1990.