Columbia subject headings:
Humboldt, Alexander von, 1769-1859--Correspondence.
Natural history--America.
Naturalists--Germany--Correspondence.
Scientists--Germany--Correspondence.
Harvard subject headings:
Humboldt, Alexander von, 1769-1859--Correspondence.
Natural history--America
Naturalists--Germany--Correspondence.
Scientists--Germany--Correspondence.
Princeton subject headings:
Finance ministers--Russia--Correspondence.
Humboldt, Alexander von, 1769-1859--Correspondence.
Kankrin, E. F. (Egor Frant︠s︡evich), graf, 1774-1845--Correspondence.
Naturalists--Germany--Correspondence.
Personal correspondence.
Russia--Description and travel.
Scientists--Germany--Correspondence.