《论衡·卷十九·验符篇》
鲁地人公孙臣，在汉文帝时说汉朝属土德，汉朝的符瑞应当是黄龙出现。
鲁人公孙臣，孝文时言汉土德，其符黄龙当见。
During Emperor Wen's reign, the Lu man Gongsuncheng said that the destiny of the Han belonged to the earth, and the auspicious sign of the Han should be the appearance of a yellow dragon.