Columbia subject headings:
Political science--History--21st century.
Political science--Philosophy.
Radicalism--History--20th century.
Harvard subject headings:
Political science--History--21st century.
Political science--Philosophy
Radicalism--History--20th century
Princeton subject headings:
Political science--History--21st century.
Political science--Philosophy.
Radicalism--History--20th century.
Radicalism.