《资治通鉴·后周纪·后周纪五》
燕王李弘冀是嫡长子又有军功，应该当继承人，谨奏奉上皇太弟的宝册。 
燕王弘冀嫡长有军功，宜为嗣，谨奉上太弟宝册。 
King of Yan, Li Hongji, is the eldest son and also has military achievements, so he should be the heir apparent. Respectfully present his highness, the Imperial younger brother, with the book of investiture.