Columbia subject headings:
Harvard subject headings:
Helmholtz, Hermann von, 1821-1894--Correspondence.
Helmholtz, Olga von, 1826-1859--Correspondence.
Physiologists--Germany--Correspondence.
Scientists--Germany--Correspondence.
Princeton subject headings:
Helmholtz, Hermann von, 1821-1894--Correspondence.
Helmholtz, Olga von, 1826-1859--Correspondence.
Scientists--Germany--Correspondence.