Columbia subject headings:
Poland--Politics and government--1918-1945.
Poland--Relations--Ukraine.
Ukraine--Politics and government--1917-1945.
Ukraine--Relations--Poland.
Harvard subject headings:
Depressions--1929
International Red Aid--History.
Labor--Poland--History.
Labor--Ukraine--History.
Poland--Relations--Ukraine
Ukraine--Relations--Poland.
Working class--Poland--History.
Working class--Ukraine--History.
Princeton subject headings:
Poland--Politics and government--1918-1945.
Poland--Relations--Ukraine.
Ukraine--Politics and government--1917-1945.
Ukraine--Relations--Poland.