《明史·志·卷六十八》
隆庆二年，提督四夷馆太常少卿武金进言： 种马制度的设立，专门为繁殖备用。
隆庆二年，提督四夷馆太常少卿武金言： 种马之设，专为孳生备用。
In the second year of the Longqing era, Wu Jin, Gentleman-in-Waiting of the Four Barbarians’ Office at the Court of Imperial Entertainment, proposed: ‘The establishment of a stud system, specifically for breeding reserves.’