21Peter S. Du Ponceau to Thomas Jefferson, 13 July 1820 (Jefferson Papers)
language; Indian (American) [index entry]
22Enclosure: Peter S. Du Ponceau’s Comparison of the Nottoway and Iroquois Languages, [ca. 13 July 1820] (Jefferson Papers)
language; Indian (American) [index entry]
23Peter S. Du Ponceau to Thomas Jefferson, 18 July 1820 (Jefferson Papers)
language; Indian (American) [index entry]
24Peter S. Du Ponceau to Thomas Jefferson, 12 September 1820 (Jefferson Papers)
language; Indian (American) [index entry]
25Peter S. Du Ponceau to Thomas Jefferson, 14 December 1820 (Jefferson Papers)
language; Indian (American) [index entry]
26John Pickering to Thomas Jefferson, 28 January 1822 (Jefferson Papers)
language; Indian (American) [index entry]
27Thomas Jefferson to John Pickering, 13 February 1822 (Jefferson Papers)
language; Indian (American) [index entry]
28Enclosure: Oliver Everett’s Advertisement for the Memoirs of the American Academy of Arts and Sciences, [ca. 22 April … (Jefferson Papers)
language; Indian (American) [index entry]