1Thomas Jefferson to John Adams, 22 August 1813 (Jefferson Papers)
Enfield, William; The History of Philosophy [index entry]
2Thomas Jefferson to John Adams, 12 October 1813 (Jefferson Papers)
Enfield, William; The History of Philosophy [index entry]
3Thomas Jefferson to John Adams, 24 January 1814 (Jefferson Papers)
Enfield, William; The History of Philosophy [index entry]
4Thomas Jefferson to John Adams, 15 August 1820 (Jefferson Papers)
Enfield, William; The History of Philosophy [index entry]