《农桑辑要·典训·先贤务农》
李衡在武陵郡龙阳洲上，修建住宅，种植了一千株柑橘，告诫儿子说： 我州里有一千头木奴，不要你供给它们吃穿，每头每年向你献上一匹绢，也可以足够用了。 
李衡于武陵龙阳洲上作宅，种甘橘千树。敕儿曰： 吾州里，有千头木奴，不责汝衣食，岁上一匹绢，亦可足用矣。 
Li Heng built a house on Longyangzhou in Wuling County and planted a thousand citrus trees, warning his son: I have a thousand wood slaves in my prefecture, I don't need you to provide them with food and clothing, each one will give you a piece of silk cloth every year, and it will be enough.