Columbia subject headings:
Age groups--United States--History--19th century.
Age groups--United States--History--20th century.
United States--Social conditions--1865-1918.
United States--Social conditions--1918-1932.
Harvard subject headings:
Age groups--United States--History--19th century.
Age groups--United States--History--20th century.
United States--Social conditions--1865-1918.
United States--Social conditions--1918-1932.
Princeton subject headings:
Age groups--United States--History--19th century.
Age groups--United States--History--20th century.
United States--Social conditions--1865-1918.
United States--Social conditions--1918-1932.