Columbia subject headings:
Harvard subject headings:
Millionaires--England--History--20th century.
Millionaires--History--20th century.
Millionaires--United States--History--20th century.
Rich people--England--History--20th century.
Rich people--History--20th century.
Rich people--United States--History--20th century.
Upper class--England--History--20th century.
Upper class--History--20th century.
Upper class--United States--History--20th century.
Princeton subject headings:
Millionaires--England--History--20th century.
Millionaires--History--20th century.
Millionaires--United States--History--20th century.
Upper class--England--History--20th century.
Upper class--History--20th century.
Upper class--United States--History--20th century.