Columbia subject headings:
Harvard subject headings:
Political science--History--19th century--Congresses.
Social Darwinism--History--19th century--Congresses.
Social sciences--History--19th century--Congresses.
Princeton subject headings:
Political science--History--19th century--Congresses.
Social Darwinism--History--19th century--Congresses.
Social sciences--History--19th century--Congresses.