1Mark Langdon Hill to Thomas Jefferson, 28 March 1820 (Jefferson Papers)
Langdon, John; correspondence with TJ [index entry]
2Thomas Jefferson to Mark Langdon Hill, 5 April 1820 (Jefferson Papers)
Langdon, John; correspondence with TJ [index entry]
3Mark Langdon Hill to Thomas Jefferson, 17 April 1820 (Jefferson Papers)
Langdon, John; correspondence with TJ [index entry]