Columbia subject headings:
Oldenburg (Germany : Landkreis)--Biography.
Peter Friedrich Ludwig, Duke of Oldenburg, 1755-1829--Childhood and youth.
Harvard subject headings:
Oldenburg (Germany : Landkreis)--Biography.
Peter Friedrich Ludwig, Duke of Oldenburg, 1755-1829--Childhood and youth.
Princeton subject headings:
Oldenburg (Germany : Landkreis)--Biography.
Peter Friedrich Ludwig, Duke of Oldenburg, 1755-1829--Childhood and youth.