Vaughan, Christopher; Mareike Schomerus and Lotje de Vries (eds). 

The Borderlands of South Sudan: Authority and Identity in Contemporary and Historical Perspectives. London/ New York: Palgrave Macmillan, 2013. 

The link to the publisher's site is here.

Moving beyond the current fixation on "state construction," the interdisciplinary work gathered here explores regulatory authority in South Sudan's borderlands from both contemporary and historical perspectives. Taken together, these studies show how emerging governance practices challenge the bounded categorizations of "state" and "non-state."