《北史·本记·卷十二》
初五，渤海贼窦建德设祭坛在河间的乐寿，自称为长乐王，建年号为丁丑。
丙辰，勃海贼窦建德设坛于河间之乐寿，自称长乐王，建元丁丑。
On the 5th, Bohai thief Dou Jiande set up an altar in L寿 of Hejian, proclaimed himself King of ChangLe, and established a reign title of Ding Chou.