Columbia subject headings:
Internal security--Ireland.
Internal security--Northern Ireland.
Terrorism--Ireland.
Terrorism--Northern Ireland.
Harvard subject headings:
Internal security--Ireland.
Internal security--Northern Ireland.
Political violence--Ireland
Political violence--Northern Ireland
Terrorism--Ireland.
Terrorism--Northern Ireland
Princeton subject headings:
Internal security--Ireland.
Internal security--Northern Ireland.
Terrorism--Ireland.
Terrorism--Northern Ireland.