The classic work is Chinese Ways in Warfare, edited by Frank A. Kierman Jr. and John K. Fairbank (Cambridge, MA: Harvard University Press, 1974), which contains detailed case studies of a number of campaigns. There is also a more recent collection of essays devoted to various battles, wars, and campaigns: Hans van de Ven, ed., Warfare in Chinese History (Leiden: E.J. Brill, 2000). Edward L. Dreyer, "Military Continuities: The PLA and Imperial China," in The Military and Political Power in China in the 1970's, edited by William W. Whitson (New York: Praeger, 1972), includes a superb overview of the patterns of warfare in Imperial China. Other articles include Benjamin E. Wallacker, "Studies in Medieval Chinese Siegecraft: The Siege of Yü-pi, A.D. 546," Journal of Asian Studies 28.4 (1969), 789-801, and David A. Graff, "The Battle of Huo-i," Asia Major (3rd Series) 5.1 (1992), 33-55.