Columbia subject headings:
Harvard subject headings:
Europe--Social conditions--20th century--Congresses.
Nineteen sixty-eight, A.D.--Political aspects--Europe--Congresses.
Protest movements--Europe--History--20th century--Congresses.
Radicalism--Europe--History--20th century--Congresses.
Student movements--Europe--History--20th century--Congresses.
Princeton subject headings:
Nineteen sixty-eight, A.D.--Congresses.
Protest movements--Europe--History--20th century--Congresses.
Radicalism--Europe--History--20th century--Congresses.