11Thomas Jefferson to Thomas Cooper, 14 August 1820 (Jefferson Papers)
The History of Philosophy (W. Enfield) [index entry]
12Thomas Jefferson to John Adams, 22 August 1813 (Jefferson Papers)
The History of Philosophy (W. Enfield) [index entry]
13Thomas Jefferson to John Adams, 15 August 1820 (Jefferson Papers)
The History of Philosophy (W. Enfield) [index entry]