《旧唐书·列传·卷三十六》
上元二年，太子从幸合璧宫，不久去世，享年二十四岁。高宗很是悲痛，因太子慈惠爱亲足以称得上孝，死而不忘君足以称得上敬，故谥号为孝敬皇帝。
居道以女为太子妃，则天时，历位纳言、内史、太子少保，封翼国公。
In the second year of the Shangyuan era, the Crown Prince Li Hong accompanied Emperor Gaozong to He璧 Palace. He died soon after at the age of 24. Emperor Gaozong was very sad. Because Li Hong was kind to his family, which showed his filial piety, and he didn't forget his respect for the Emperor before he died, Emperor Gaozong granted Li Hong the posthumous title "Filial and Respectful Emperor."