1Thomas Jefferson to Alexander von Humboldt, 6 March 1809 (Jefferson Papers)
Bonpland, Aimé Goujaud; Voyage de Humboldt et Bonpland [index entry]
2John Vaughan to Thomas Jefferson, 20 August 1809 (Jefferson Papers)
Bonpland, Aimé Goujaud; Voyage de Humboldt et Bonpland [index entry]