Columbia subject headings:
Belgium--Colonies--Africa.
Mineral industries--Congo (Democratic Republic)--History.
Miners--Congo (Democratic Republic)--History.
Working class--Congo (Democratic Republic)--History.
Harvard subject headings:
Belgium--Colonies--Africa.
Mineral industries--Congo (Democratic Republic)--History.
Miners--Congo (Democratic Republic)--History.
Working class--Congo (Democratic Republic)--History.
Princeton subject headings:
Belgium--Colonies--Africa.
Mineral industries--Congo (Democratic Republic)--History.
Miners--Congo (Democratic Republic)--History.
Working class--Congo (Democratic Republic)--History.