Burr, Millard; Robert O. Collins (1995). Requiem for the Sudan: War, Drought, and Disaster Relief on the Nile. Westview Press. p. 18. ISBN0-8133-2121-2.; online at Google Books
Course info mainly from: Illustrated Atlas of the World (1994 Revised ed.). Rand McNally. 1992. pp. 184 (Map 35: East-Central Africa. ISBN0-528-83492-4.; and Shahin, Mamdouh (2002). Hydrology and Water Resources of Africa. Springer. p. 276. ISBN1-4020-0866-X.; online at Google Books
Cohen, Roberta (1998). The Forsaken People: Case Studies of the Internally Displaced. Brookings Institution Press. p. 144. ISBN0-8157-1513-7.; online at Google Books
Burr, Millard; Robert O. Collins (1995). Requiem for the Sudan: War, Drought, and Disaster Relief on the Nile. Westview Press. pp. 17–19, 81. ISBN0-8133-2121-2.; online at Google Books