: geographical distribution and dynamics in relation to the ecology of West Africa, 1999. pp. 44-50. London: Overseas Development Institute.
 Chambers, R., and G. R. Conway, Sustainable rural livelihoods: practical concepts for the 21st century, Institute for Development Studies Discussion Paper, 1991; 296.
 FAO, World Watch List for Domestic Animal Diversity. Third Edition. Food and Agriculture Organization of the United Nations (FAO), Rome, Italy, 2000. 726 p.
 Gandini, Gustavo C., and Emanuele Villa, Analysis of the