《隋书·列传·卷十》
另外，维城建帜，加重威权，恃宠而骄，多自封植，进而超过规矩，退而不依其道，杨俊忧郁而死，实在是由于这个缘故。
又维城肇建，崇其威重，恃宠而骄，厚自封植，进之既逾制，退之不以道。俊以忧卒，实此之由。
Besides, the erection of banners in Weicheng reinforced the authority and made people arrogant because of being favored. They planted themselves without authorization, went beyond the rules, and refused to follow the right path, which was definitely the reason why Yang Jun died of distress.