《北史·本记·卷十二》
秋七月初四，启民可汗上表请求改变原服饰，袭用中原冠带。
秋七月辛亥，启民可汗上表请变服，袭冠带。
On the first part of July in the autumn, Qimin Khan submitted a memorial requesting to change his original costumes and wear the crown and belt of the Central Plains.