《旧唐书·本纪·卷十七》
初六，通化南北二门锁不能开，钥匙插入，像有东西夹住。
己卯，通化南北二门锁不可开，钥入，如有持之者。
On the sixth day, the locks on the two main gates of Tongcheng, North and South, could not be opened; the keys were inserted, as if something was blocking them.