《新五代史·列传·杂传第四十二》
后来游历关中，刘季述把唐昭宗幽囚在束内，李愚写信游说韩建，要他图谋复兴，言辞十分雄壮。
后游关中，刘季述幽昭宗于东内，愚以书说韩建，使图兴复，其言甚壮。
Later, when traveling in Guanzhong, Liu Jishu imprisoned Emperor Zhaozong of Tang in Shu, Li Yu wrote a letter to persuade Han Jian, asking him to plan a restoration, the words were very eloquent.