Columbia subject headings:
Africa, Central--History--To 1884.
Africa, Southern--History--To 1899.
Kasai River Watershed (Angola and Congo)--Commerce--History.
Zambezi River Watershed--Commerce--History.
Harvard subject headings:
Africa, Central--History--To 1884.
Africa, Southern--History--To 1899.
Kasai River Watershed (Angola and Congo)--Commerce--History.
Zambezi River Watershed--Commerce--History.
Princeton subject headings:
Africa, Central--History--To 1884.
Africa, Southern--History--To 1899.
Kasai River Watershed (Angola and Congo)--Commerce--History.
Zambezi River Watershed--Commerce--History.