1Thomas Jefferson to Horatio G. Spafford, 14 May 1809 (Jefferson Papers)
2Johann Severin Vater to Thomas Jefferson, 4 November 1809 (Jefferson Papers)
3Horatio G. Spafford to Thomas Jefferson, 14 January 1810 (Jefferson Papers)
4Henry M. Brackenridge to Thomas Jefferson, 25 July 1813 (Jefferson Papers)