Columbia subject headings:
Naturalists--United States--Correspondence.
Xántus, János, 1825-1894--Correspondence.
Harvard subject headings:
Naturalists--United States--Correspondence
Xántus, János, 1825-1894--Correspondence.
Princeton subject headings:
Naturalists--United States--Correspondence.
Xántus, János, 1825-1894--Correspondence.