《黄帝内经·素问·玉版论要》
脸部面色的变化，表现在上下左右不同的部位，应分别审察其主病的要领。
容色见上下左右，各在其要。
The changes in the complexion of the face are manifested in different parts of the upper, lower, left and right, and the key points of the main diseases should be examined separately.