Columbia subject headings:
Middle class--United States--Social conditions.
Social mobility--United States.
United States--Economic conditions--1981-2001.
United States--Social conditions--1980-2020.
Harvard subject headings:
Middle class--United States.
Social mobility--United States.
United States--Economic conditions--1981-2001.
United States--Social conditions--1980-2020
Princeton subject headings:
Middle class--United States--Social conditions.
Social mobility--United States.
United States--Economic conditions--1981-2001.
United States--Social conditions--1980-2020.