Columbia subject headings:
Harvard subject headings:
Baltic States--History--Revolution, 1917-1921.
Germany--History.
Hamm (North Rhine-Westphalia, Germany)--History.
North Rhine-Westphalia (Germany)--Economic conditions.
North Rhine-Westphalia (Germany)--Politics and government.
Political culture--Europe.
Regionalism--Germany--North Rhine-Westphalia--History.
Ruhr (Germany : Region)--History
Winnig, August, 1878-1956.
Princeton subject headings:
Germany--Historiography.
Germany--History, Local.
Local history.