(en) Thurstan Shaw, The Archaeology of Africa: Food, Metals and Towns, Routledge, (ISBN0-415-11585-X, lire en ligne), p. 275
(en) James R. Penn, Rivers of the world: a social, geographical, and environmental sourcebook, ABC-CLIO, (ISBN1-57607-042-5, lire en ligne), p. 26
(en) Hope B. Werness, The Continuum Encyclopedia of Native Art: Worldview, Symbolism, and Culture in Africa, Oceania, and North America, Continuum International Publishing Group, (ISBN0-8264-1465-6, lire en ligne), p. 223
(en) G. Mokhtar, Ancient civilizations of Africa, University of California Press, (ISBN0-435-94805-9, lire en ligne), p. 611
(en) Elizabeth Allo Isichei, A history of African societies to 1870, Cambridge University Press, (ISBN0-521-45599-5, lire en ligne), p. 70