1Thomas Jefferson to Alexander von Humboldt, 6 March 1809 (Jefferson Papers)
Bonpland, Aimé Goujaud; Voyage de Humboldt et Bonpland [index entry] Humboldt, Friedrich Wilhelm Heinrich Alexander, Baron von; 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] Humboldt, Friedrich Wilhelm Heinrich Alexander, Baron von; Voyage de Humboldt et Bonpland [index entry]
3To James Madison from Friedrich Wilhelm Heinrich Alexander von Humboldt, 23 September 1810 (Abstract) (Madison Papers)
. This work was published in installments in Paris between 1808 and 1813, and it formed part of Humboldt’s magnum opus, Voyage de Humboldt et Bonpland (see Sowerby,