《后汉书·列传·方术列传下》
郭玉年轻时曾拜程高为师，学习方诊六微的技巧，阴阳推算的方法。
玉少师事高，学方诊六微之技，阴阳隐侧之术。
When he was young, Guo Yu visited Cheng Gao to learn the skill of six tiny diagnoses and the methods of divinations based on yin and yang.