Cheng-hua: Year 2, Month 7, Day 18
28 Aug 1466
The attendant minister Ruan Shi-xing and others who had been sent by Li Hao, the king of the country of Annam, came to Court with a memorial, a salutory letter and tribute of local products. Clothing, variegated silks and other goods were conferred upon them. Annam was required to offer tribute once every three years and the tribute brought on this occasion was the tribute due in accordance with this requirement.
Zhong-yang Yan-jiu yuan Ming Shi-lu, volume 40, page 639