Columbia subject headings:
Harvard subject headings:
Left-wing extremists--Europe--Congresses.
Political participation--Europe--Congresses.
Radicalism--Europe--Congresses.
Right and left (Political science)--Europe--Congresses.
Social classes--Political aspects--Europe--Congresses.
Princeton subject headings:
Left-wing extremists--Europe--Congresses.
Political participation--Europe--Congresses.
Radicalism--Europe--Congresses.
Right and left (Political science)--Europe--Congresses.
Social classes--Political aspects--Europe--Congresses.