1Thomas Jefferson to Isaac Doolittle, 18 September 1813 (Jefferson Papers)
2Thomas Jefferson to Destutt de Tracy, 28 November 1813 (Jefferson Papers)
3Thomas Jefferson to Pierre Samuel Du Pont de Nemours, 29 November-14 December 1813 (Jefferson Papers)
4Thomas Jefferson to Pierre Samuel Du Pont de Nemours, 3 August 1816 (Jefferson Papers)