《汉书·纪·武帝纪》
三月，下诏说： 根据有关官员的建议，前一段朕郊祭上天，西登陇首山，获得白麒麟以献于祖庙，渥洼水出天马，泰山出现自然黄金，应表祥瑞而改旧法。
三月，诏曰： 有司议曰，往者朕郊见上帝，西登陇首，获白麟以馈宗庙，渥洼水出天马，泰山见黄金，宜改故名。
In March, an imperial edict was issued stating: According to the suggestions of the relevant officials, I recently offered sacrifices to the heaven outside the suburbs, ascended the Longshou Mountain in the West, and obtained a white unicorn which was presented to the ancestral temple. The Wowa water gave birth to a celestial horse, and the Tai Mountain produced natural gold. We should express our joy at these lucky events by changing the old laws.