隋书
According to the "Book of Sui", Zhangchou Taiyi (章仇太翼), a native of Hejian Commandery (in modern Cangzhou, Hebei) was a famous scholar of the time. Emperor Yang of Sui granted him the surname Lu 卢. Zhangchou subsequently became known as Lu Taiyi, and was the ancestor of the prosperous Hejian Lu clan.