Columbia subject headings:
Capitalism--United States--History--20th century.
Labor unions--Organizing--United States--History--20th century.
Marxian economics.
Social classes--United States--History--20th century.
Socialism--United States--History--20th century.
Harvard subject headings:
Capitalism--United States--History--20th century.
Labor unions--Organizing--United States--History--20th century.
Marxian economics.
Social classes--United States--History--20th century.
Socialism--United States--20th century.
Socialism--United States--History--20th century
Princeton subject headings:
Capitalism--United States--History--20th century.
Labor unions--Organizing--United States--History--20th century.
Marxian economics.
Social classes--United States--History--20th century.
Socialism--United States--History--20th century.