11Alexander von Humboldt to Thomas Jefferson, 26 December 1811 (Jefferson Papers)
Pour ne pas ouvrir une longue lettre que j’ai eu l’honneur de Vous adresser par l’intremise de Mr...
12Thomas Jefferson to Alexander von Humboldt, 6 December 1813 (Jefferson Papers)
I have to acknolege your two letters of Dec. 20. & 26. 1811. by mr Correa , and am first to thank...
13Thomas Jefferson to Alexander von Humboldt, 13 June 1817 (Jefferson Papers)
The reciept of your Distributio geographica plantarum, with the duty of thanking you for a work...