Columbia subject headings:
Oldenburg (Grand Duchy)--Foreign relations.
Oldenburg (Grand Duchy)--History--Sources.
Oldenburg (Grand Duchy)--Politics and government--18th century.
Oldenburg (Grand Duchy)--Politics and government--19th century.
Peter Friedrich Ludwig, Duke of Oldenburg, 1755-1829--Political and social views.
Peter Friedrich Ludwig, Duke of Oldenburg, 1755-1829--Will.
Harvard subject headings:
Princeton subject headings:
Oldenburg (Grand Duchy)--Foreign relations.
Oldenburg (Grand Duchy)--History--Sources.
Oldenburg (Grand Duchy)--Politics and government--18th century.
Oldenburg (Grand Duchy)--Politics and government--19th century.
Peter Friedrich Ludwig, Duke of Oldenburg, 1755-1829--Political and social views.
Peter Friedrich Ludwig, Duke of Oldenburg, 1755-1829--Will.