“Enclosure: Thomas Jefferson’s Paper Model of Thomas Mann Randolph’s Plow, [ca. 2 May 1817],” Founders Online, National Archives, https://founders.archives.gov/documents/Jefferson/03-11-02-0270-0002. [Original source: The Papers of Thomas Jefferson, Retirement Series, vol. 11, 19 January to 31 August 1817, ed. J. Jefferson Looney. Princeton: Princeton University Press, 2014, p. 311.]