Snow, P. 1989. The Star Raft. China's Encounter with Africa. Ithaca, NY, Cornell University Press.  
Tuotuo et al. 1977. Songshi [History of the Song]. Beijing, Zhonghua shuju. (In Chinese.)
Watson, J. L. 1980. Introduction. Slavery as an Institution, Open and Closed Systems. J. L. Watson (ed.), Asian and African Systems of Slavery. Berkeley, Calif., University of California Press, pp. 1-15.  
Wilkinson, E. 2015 (orig. pub. 1973). Chinese History. A New Manual, 4th ed. Cambridge, Mass., Harvard University Asia Center.  
Wyatt, D. J. 2010. The Blacks of Premodern China. Philadelphia, Penn., University of Pennsylvania Press.  
Zhu, M. 2003. Fangyu shenglan [Topographical Guide for Visiting Sites of Scenic Beauty]. Beijing, Zhonghua shuju. (In Chinese.)  
Zhu, Y. 1921. Pingzhou ketan [Pingzhou Chats on Things Worthwhile]. Shanghai, Bogu zhai. (In Chinese.)