Columbia subject headings:
Harvard subject headings:
Forced migration--History--20th century.
International law.
Population transfers--History--20th century.
Refugees--Europe, Central--History--20th century.
Refugees--Europe--History--20th century.
Refugees--International cooperation
Princeton subject headings:
Europe--Politics and government--20th century.
Forced migration--Europe--History--20th century.
Genocide--Europe--History--20th century.