Columbia subject headings:
Radicalism--History--21st century.
Security, International.
Terrorism--History--21st century.
Harvard subject headings:
Arts--21st century--Themes, motives.
Radicalism--Europe--History--21st century.
Radicalism--History--21st century.
Security, International
Terrorism--Europe--History--21st century.
Terrorism--Europe--Prevention--History--21st century.
Terrorism--History--21st century.
Terrorism--Prevention--History--21st century.
Terrorism--Prevention--Law and legislation--Europe--History--21st century.
Princeton subject headings:
Radicalism--History--21st century.
Security, International.
Terrorism--History--21st century.