Yousif, H.M. <https://pure.iiasa.ac.at/view/iiasa/1674.html> ORCID: https://orcid.org/0000-0001-8071-1395 <https://orcid.org/0000-0001-8071-1395>  (1994).  Population, Biomass and the Environment in Central Sudan.   IIASA Working Paper. IIASA, Laxenburg, Austria: WP-94-108