《汉书·传·武五子传》
当初，昭帝在位时，刘胥见皇帝年少又没有儿子，就产生了觊觎帝位之心。
始，昭帝时，胥见上年少无子，有觊欲心。
Originally, when Emperor Zhao was on the throne, Liu Xu saw that the emperor was young and had no sons, so he developed ambitions to usurp the emperor's throne.