《宋书·志·卷十九》
宫声的竹管放在中央。有三十六个簧片称为竽，宫声的竹管放在左边。在十九簧到十三簧之间的称为笙。
宫管在中央，三十六簧曰竽；宫管在左傍，十九簧至十三簧曰笙。
The bamboo pipe with the palace sound is placed in the center. There are thirty-six reeds called yu, and the bamboo pipe with the palace sound is placed on the left. Between nineteen and thirteen reeds, it is called sheng.