De Crespigny, Rafe. "The Government and Geography of the Northern Frontier of Late Han". Australian National University, 2004. A revised version of "Northern Frontier: the Policies and Strategy of the Later Han Empire", Asian Studies Monographs New Series, No. 4, 1984. ISBN 0-86784-410-8. Accessed 12 Dec 2013.
books.google.com
Olberding, Garret. Dubious Facts: The Evidence of Early Chinese Historiography, pp. 183 ff. SUNY Press, 2012. Accessed 12 Dec 2013.
