Columbia subject headings:
Natural history--United States--Bibliography--Union lists.
Natural history--United States--History--Sources--Bibliography--Union lists.
Harvard subject headings:
Natural history--United States--Bibliography--Union lists.
Natural history--United States--History--Sources--Bibliography--Union lists.
Princeton subject headings:
Natural history--United States--Bibliography--Union lists.
Natural history--United States--History--Sources--Bibliography--Union lists.