Columbia subject headings:
Harvard subject headings:
Consuls--Europe--History--19th century.
Diplomatic and consular service, European--History--19th century.
Diplomatic and consular service--Europe--History--19th century.
Diplomatic and consular service--History--19th century.
Princeton subject headings:
Consuls--History--19th century.
Diplomatic and consular service--History--19th century.
International relations--History--19th century.