《资治通鉴·隋纪·隋纪五》
杨认为元德太子有三个儿子，恐怕自已不能被立为太子，暗中倚靠左道妖术作咒诅以求胜，到后来这些都被揭发。
暕以元德太子有三子，恐不得立，阴挟左道为厌胜，至是皆发。
Yang believed that Crown Prince Yuand De had three sons, and he was afraid that he would not be established as crown prince, so he secretly relied on occult techniques and incantations to seek victory, but this was later exposed.