《资治通鉴·唐纪·唐纪五十二》
根据晋朝庾蔚之的说法，倘若寻找亲人已经超过三年仍未找到，便可以等到他八十岁诞辰时，为他服丧。
案晋庾蔚之议，寻求三年之外，俟中寿而服之。
According to Yu Weizhi of the Jin Dynasty, if after three years a missing relative has not been found, he should be mourned when he would have reached the age of eighty.