《明史·志·卷五十七》
永乐二年，恢复设置宝泉局，铸造小钱，与钞一同流通，一百文以下只用钱。
越二年，复设宝泉局，铸小钱与钞兼行，百文以下止用钱。
In the second year of the Yongle reign, the Baoquan Bureau was re-established to cast small coins, which circulated together with notes. Only coins were used for transactions of one hundred wen or less.