《资治通鉴·唐纪·唐纪二十九》
辛巳，唐玄宗下令，由于民间多偷着铸造钱币，从现在开始禁止私自出卖铜铅锡以及用铜制造器皿；开采的铜铅锡，由官方收购。
辛巳，敕以人间多盗铸钱，始禁私卖铜铅锡及以铜为器皿；其采铜铅锡者，官为市取。
In Xinsi, Emperor Xuanzong of the Tang Dynasty ordered that since there were many private casting of coins among the people, from now on, it would be forbidden to privately sell copper, lead, and tin or to make utensils with copper; the mined copper, lead, and tin would be purchased by the government.