Columbia subject headings:
Harvard subject headings:
Africa--Colonization--History--Congresses.
Colonies--Africa--History--Congresses.
Colonies--History--Congresses.
Colonization--History--Congresses.
Working class--Africa--History--Congresses.
Working class--History--Congresses.
Princeton subject headings:
Africa--Colonization--History--Congresses.
Colonies--Africa--History--Congresses.
Colonies--History--Congresses.
Colonization--History--Congresses.
Working class--Africa--History--Congresses.
Working class--History--Congresses.