1Thomas Jefferson to Joseph Milligan, 9 December 1818 (Jefferson Papers)
Euclid; The Elements of Euclid (R. Simson) [index entry] The Elements of Euclid (R. Simson) [index entry]
2George Blackburn to Thomas Jefferson, 8 March 1819 (Jefferson Papers)
Euclid; The Elements of Euclid (R. Simson) [index entry] The Elements of Euclid (R. Simson) [index entry]