Columbia subject headings:
Helmholtz, Hermann von, 1821-1894--Correspondence.
Physiologists--Germany--Correspondence.
Scientists--Germany--Correspondence.
Harvard subject headings:
Helmholtz, Hermann von, 1821-1894--Correspondence.
Helmholtz, Hermann von, 1821-1894--Language.
Scientists--Germany--Correspondence.
Princeton subject headings:
Helmholtz, Hermann von, 1821-1894--Correspondence.
Physiologists--Germany--Correspondence.
Scientists--Germany--Correspondence.