1Thomas Jefferson to Alexander von Humboldt, 6 March 1809 (Jefferson Papers)
Bonpland, Aimé Goujaud; Voyage de Humboldt et Bonpland [index entry] Voyage de Humboldt et Bonpland
2John Vaughan to Thomas Jefferson, 20 August 1809 (Jefferson Papers)
Bonpland, Aimé Goujaud; Voyage de Humboldt et Bonpland [index entry] Voyage de Humboldt et Bonpland
3To James Madison from Friedrich Wilhelm Heinrich Alexander von Humboldt, 23 September 1810 (Abstract) (Madison Papers)
..., and it formed part of Humboldt’s magnum opus, Voyage de Humboldt et Bonpland (see Sowerby,