1Destutt de Tracy to Thomas Jefferson, 24 December 1816 (Jefferson Papers)
2Robert Walsh to Thomas Jefferson, 27 January 1818 (Jefferson Papers)
3Robert Walsh to Thomas Jefferson, 12 March 1818 (Jefferson Papers)
4Destutt de Tracy to Thomas Jefferson, 11 April 1818 (Jefferson Papers)
5Robert Walsh to Thomas Jefferson, 20 April 1818 (Jefferson Papers)
6Destutt de Tracy to Thomas Jefferson, 22 February 1821 (Jefferson Papers)