《资治通鉴·魏纪·魏纪八》
李丰担任中书令的两年中，皇帝多次召见李丰一起交谈，但不知说些什么。
丰在中书二岁，帝数独召丰与语，不知所说。
During the two years that Li Feng served as Minister of Central Secretariat, the emperor summoned Li Feng to talk with him several times, but did not know what to say.