Christiansen, S. (1995) “H. Breman & J.-J. Kessler: Woody Plants in Agro-Ecosystems of Semi-Arid Regions, - with emphasis on the Sahelian countries. - (Advances series in Agricultural Sciences 23)”., Geografisk Tidsskrift, 95. Tilgængelig hos: https://tidsskrift.dk/geografisktidsskrift/article/view/42057 (Set: 5 december 2025).