Columbia subject headings:
Communism--Germany--History--Chronology.
Socialism--Germany--History--Chronology.
Harvard subject headings:
Communism--Germany--History--Chronology.
Socialism--Germany--Chronology.
Socialism--Germany--History--Chronology.
Princeton subject headings:
Communism--Germany--History--Chronology.
Socialism--Germany--History--Chronology.