Columbia subject headings:
Du Bois-Reymond, Emil, 1818-1896.
Ludwig, Carl, 1816-1895.
Physiologists--Germany--Biography.
Physiologists--Germany--Correspondence.
Harvard subject headings:
Du Bois-Reymond, Emil, 1818-1896.
Ludwig, Carl, 1816-1895.
Physiologists--Germany--Biography.
Physiologists--Germany--Correspondence.
Princeton subject headings:
Du Bois-Reymond, Emil, 1818-1896.
Ludwig, Carl, 1816-1895.
Physiologists--Germany--Biography..
Physiologists--Germany--Correspondence.