Columbia subject headings:
Niger River Delta (Nigeria)--Commerce.
Niger River Delta (Nigeria)--Economic conditions--18th century.
Niger River Delta (Nigeria)--Economic conditions--19th century.
Niger River Delta (Nigeria)--Politics and government--18th century.
Niger River Delta (Nigeria)--Politics and government--19th century.
Harvard subject headings:
Nigeria, Eastern--Commerce--History.
Nigeria, Eastern--History.
Nigeria, Eastern--Kings and rulers.
Nigeria, Eastern--Politics and government.
Princeton subject headings: