《资治通鉴·后周纪·后周纪五》
丝、竹？土等各种质地的乐器也只有七个声音，称为黄钟之宫，保存下来的有九个曲子。
丝、竹、匏、土仅有七声，名为黄钟之宫，其存者九曲。
Silk, bamboo, soil, etc. Musical instruments of various textures have only seven sounds, called Huangzhong Palace, and there are nine surviving songs.