* Hartwell, Robert M. "Demographic, Political, and Social Transformations of China, 750–1550," "Harvard Journal of Asiatic Studies", Volume 42, Number 2 (1982): 365–442.
* Hartwell, Robert M. «Demographic, Political, and Social Transformations of China, 750—1550,» "Harvard Journal of Asiatic Studies", Volume 42, Number 2 (1982): 365—442.