《资治通鉴·唐纪·唐纪六十五》
王端章被派往安西册立回鹘可汗，因道路被黑车子所堵塞，没有到达目的地而返回。
王端章册立回鹘可汗，道为黑车子所塞，不至而还。
Wang Duanzhang was sent to Anxi to enthrone the Uighur Khan, but he did not reach his destination and returned because the road was blocked by black carts.