Columbia subject headings:
Lens, Sidney.
Radicalism--United States.
Socialism--United States.
Socialists--United States--Biography.
Harvard subject headings:
Lens, Sidney.
Radicalism--United States.
Socialism--United States
Socialists--United States--Biography
Princeton subject headings:
Lens, Sidney.
Radicalism--United States.
Socialism--United States.
Socialists--United States--Biography.