Columbia subject headings:
Genocide--Europe--History--20th century--Congresses.
Holocaust, Jewish (1939-1945)--Congresses.
Political persecution--Europe--History--20th century--Congresses.
Harvard subject headings:
GULag NKVD--Congresses.
Genocide--Congresses.
Holocaust, Jewish (1939-1945)--Congresses
Princeton subject headings:
Genocide--Europe--History--20th century--Congresses.
Holocaust, Jewish (1939-1945)--Congresses.
Political persecution--Europe--History--20th century--Congresses.