Columbia subject headings:
Harvard subject headings:
Germany--Social conditions--20th century.
Occupational mobility--Germany--History--20th century.
Occupational mobility--United States--History--20th century.
Social classes--Germany--History--20th century.
Social classes--United States--History--20th century.
Social mobility--Germany--History--20th century.
Social mobility--History--20th century.
Social mobility--United States--History--20th century.
United States--Social conditions--20th century.
Princeton subject headings:
Germany--Social conditions--20th century.
Occupational mobility--Germany--History--20th century.
Occupational mobility--United States--History--20th century.
Social classes--Germany--History--20th century.
Social classes--United States--History--20th century.
Social mobility--Germany--History--20th century.
Social mobility--History--20th century.
Social mobility--United States--History--20th century.
United States--Social conditions--20th century.