1. Allan, William: The African husbandman. Oliver and Boyd, Edinburgh 1965.
2. Amerena, P.M.J.: Farmers' participation in the cash economy: case studies of two settlements in the Kano Close-Settled Zone of Nigeria. Ph.D. thesis, University of London, 1982.
3. Bahemuka, J. Mbula; Tiffen. M.; Kaluli. J.W.: Environmental change and dryland management in Machakos District, Kenya, 1930?1990. Institutional Profile. Working Paper 62. Overseas Development Institute, London 1991.
4. Boserup, Ester: The conditions of agricultural growth. Allen and Unwin, London 1965.
5. Boulier, F.; Jouve, Ph.: Etude comparée de l'evolution des systémes de production Saheliens et de leur adaptation a la sécheresse. Département de Systémes Agraires, Montpellier 1988.