1Peter S. Du Ponceau to Thomas Jefferson, 5 December 1817 (Jefferson Papers)
American Philosophical Society, Historical and Literary Committee; and W. Byrd manuscripts [index entry]
2Peter S. Du Ponceau to Thomas Jefferson, 6 January 1818 (Jefferson Papers)
American Philosophical Society, Historical and Literary Committee; and W. Byrd manuscripts [index entry]
3Peter S. Du Ponceau to Thomas Jefferson, 24 January 1818 (Jefferson Papers)
American Philosophical Society, Historical and Literary Committee; and W. Byrd manuscripts [index entry]
4Peter S. Du Ponceau to Thomas Jefferson, 24 February 1818 (Jefferson Papers)
American Philosophical Society, Historical and Literary Committee; and W. Byrd manuscripts [index entry]