《资治通鉴·唐纪·唐纪六十七》
元密等人认为叛贼必定要固守宿州城，只为攻城考虑计策。
元密等以为贼必固守，但为攻取之计。
Yuan Mi and others believed that the rebels must be determined to defend Suzhou from within the city walls, and only considered strategies for sieges.