1Thomas Jefferson to Alexander von Humboldt, 6 March 1809 (Jefferson Papers)
Humboldt, Friedrich Wilhelm Heinrich Alexander, Baron von; Recueil d’observations astronomiques [...
2Alexander von Humboldt to Thomas Jefferson, 12 June 1809 (Jefferson Papers)
Humboldt, Friedrich Wilhelm Heinrich Alexander, Baron von; Recueil d’observations astronomiques [...
3John Vaughan to Thomas Jefferson, 20 August 1809 (Jefferson Papers)
Humboldt, Friedrich Wilhelm Heinrich Alexander, Baron von; Recueil d’observations astronomiques [...
4Alexander von Humboldt to Thomas Jefferson, 20 December 1811 (Jefferson Papers)
Humboldt, Friedrich Wilhelm Heinrich Alexander, Baron von; Recueil d’observations astronomiques [...
5Thomas Jefferson to Alexander von Humboldt, 6 December 1813 (Jefferson Papers)
Humboldt, Friedrich Wilhelm Heinrich Alexander, Baron von; Recueil d’observations astronomiques [...