《宋史·列传·卷九十六》
范镇说 ：定乐应当先订正律吕。 神宗说： 对，即使有师旷的聪慧，不用六律也不能订正五音。 范镇制作律尺、龠合、升斗、豆区、斛，打算把它们绘成图呈上，又请求访求真黍，以定黄钟。
镇曰： 定乐当先正律。 神宗曰： 然，虽有师旷之聪，不以六律不能正五音。 镇作律尺、龠合、升斗、豆区、鬴斛，欲图上之，又乞访求真黍，以定黄钟。
Fan Zhen said: “In order to revise the music, it should first be tuned correctly.” Emperor Shenzong said: “That is right; even if one were as clever as Shi Kuang, one could not tune the five notes correctly without using the six pitches.” Fan Zhen then made a pitch ruler, a “yuehe” pitch pipe, a “shengdou” volume measure, a “douqu” capacity measure and a “hu” volume measure, and intended to draw up a plan of them to submit to the emperor, and he also requested that he should be allowed to seek the real husked millet so as to determine the pitch of the Huang Zhong pitch.