《宋书·志·卷十一》
另外，笛子的各孔虽然没有校试，但从意义上说不可能一孔就与一律相对应。 
又笛诸孔，虽不校试，意谓不能得一孔辄应一律也。 
Besides, although there has been no examination of each hole of the flute, it is impossible for one hole to correspond to one law in terms of meaning.