《论衡·卷三·奇怪篇》
谶书上又说： 尧的母亲庆都到野外去，遇上赤龙冲动与之交合，于是生下尧。 
谶书又言： 尧母庆都野出，赤龙感己，遂生尧 。
The prophetic book also said: Yao's mother Qing Du went to the wild to meet a red dragon impulse and had sex with it, so she gave birth to Yao.