《晋书·志·第六章》
夷则之笛，正声应合夷则律，下征应合夹钟律，长三尺六寸。
夷则之笛，正声应夷则，下徵应夹钟，长三尽六寸。
The reed pipe of Yi is in harmony with the Yi law, and the law of Jiazhong together with the sub-rule, and is three feet and six inches in length.