1From Thomas Jefferson to Alexander von Humboldt, 28 May 1804 (Jefferson Papers)
I recieved last night your favor of the 24th. and offer you my congratulations on your arrival...
2From Thomas Jefferson to Alexander von Humboldt, 9 June 1804 (Jefferson Papers)
Thos: Jefferson asks leave to observe to Baron de Humboldt that the question of limits of...
3Thomas Jefferson to Alexander von Humboldt, 6 March 1809 (Jefferson Papers)
I recieved safely your letter of May 30. & with it your astronomical work & Political essay on...
4Thomas Jefferson to Alexander von Humboldt, 14 April 1811 (Jefferson Papers)
The interruption of our intercourse with France , for some time past, has prevented my writing to...
5Thomas 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...
6Thomas 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...