• 杜佑 Tu Yu (died 812) did not publish a separate commentary on Sun Tzǔ , his notes being taken from the Tʽung Tien , the encyclopedic treatise on the Constitution which was his lifework. They are largely repetitions of Tsʽao Kung and Mêng Shih , besides which it is believed that he drew on the ancient commentaries of 王凌 Wang Ling and others. Owing to the peculiar arrangement of Tʽung Tien , he has to explain each passage on its merits, apart from the context, and sometimes his own explanation does not agree with that of Tsʽao Kung , whom he always quotes first. Though not strictly to be reckoned as one of the “Ten Commentators,” he was added to their number by Chi Tʽien-pao , being wrongly placed after his grandson Tu Mu .