DeLancey, Virginia (2015). 〈Energy〉(PDF). Berry, LaVerle. 《Sudan : a country study》 5판. Washington, D.C.: Federal Research Division, Library of Congress. 192–196쪽. ISBN978-0-8444-0750-0. 이 문서는 퍼블릭 도메인 출처의 본문을 포함합니다. Though published in 2015, this work covers events in the whole of Sudan (including present-day South Sudan) until the 2011 secession of South Sudan.