Columbia subject headings:
Harvard subject headings:
Bunsen, R. (Robert), 1811-1899--Correspondence.
Bunsen, R. (Robert), 1811-1899.
Chemistry--Europe--History--19th century.
Chemists--Europe--Correspondence.
Chemists--Germany--Correspondence.
Princeton subject headings:
Bunsen, R. (Robert), 1811-1899.
Chemistry--Europe--History--19th century.
Chemists--Europe--Correspondence.