Hans Ruthenberg,

Farming Systems in the Tropics , 2nd edn. (Clarendon Press, 1976).

Ester Boserup,

The Conditions of Agricultural Growth (Allen & Unwin, 1965).

Charles H. Feinstein,

An Economic History of South Africa: Conquest, Discrimination and Development (Cambridge University Press, 2005).

R. S. O’Fahey,

The Darfur Sultanate: A History (Hurst, 2008).

Roland Dumont, Alexandre Dansi, Philippe Vernier, and Jeanne Zoundjihèkpon,

Biodiversity and Domestication of Yams in West Africa: Traditional Practices Leading to Dioscorea Rotundata Poir (CIRAD, 2005).

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