《太平广记·卷二百零五·乐三》
李皋说： 这两付羯鼓卷定然是开元、天宝年间，向朝廷供奉的御卷。不然没有这么高质量的好卷。 
皋曰：此必开元天宝中供御卷，不然无以至此。
Li Gao declared, "These two scrolls must have been imperial drumsticks dating back to the Kaiyuan or Tianbao eras. Otherwise, they would not be of such high quality."