Columbia subject headings:
Harvard subject headings:
Crimes against humanity--History--20th century.
Genocide--History--20th century.
Massacres--History--20th century.
Political violence--History--20th century.
Prejudices--History--20th century.
Princeton subject headings:
Crimes against humanity--History--20th century.
Genocide--History--20th century.
Prejudices--History--20th century.