Columbia subject headings:
Harvard subject headings:
Humboldt, Alexander von, 1769-1859--Correspondence.
Librarians--Germany--Correspondence.
Newspaper editors--Germany--Correspondence.
Scientists--Germany--Correspondence.
Spiker, Samuel Heinrich, 1786-1858--Correspondence.
Princeton subject headings:
Humboldt, Alexander von, 1769-1859--Correspondence.
Spiker, Samuel Heinrich, 1786-1858--Correspondence.