New Works in West African Economic History - Middlemen of the Cameroons River: The Duala and their Hinterland, c. 1600–c.1960. By Ralph A. Austen and Jonathan Derrick. Cambridge: Cambridge University Press, 1999. Pp. vii, 252. $64.95, cloth; $24.95, paper. - EI Dorado in West Africa: The Gold-Mining Frontier, African Labor, and Colonial Capitalism in the Gold Coast, 1875–1900. By Raymond E. Dumett. Athens, OH: Ohio University Press, 1998. Pp. viii, 396. $44.95, cloth; $19.95, paper. - Slavery and Colonial Rule in French West Africa. By Martin A. Klein. Cambridge: Cambridge University Press, 1998. Pp. xxi, 354 $54.95, cloth; $19.95, paper.