Columbia subject headings:
Electronic surveillance--United States.
Terrorism--United States--Prevention.
Terrorists--United States.
War on Terrorism, 2001-2009.
Harvard subject headings:
Electronic surveillance--United States
Terrorism--United States--Prevention
Terrorists--United States
War on Terrorism, 2001-2009
Princeton subject headings:
Electronic surveillance--United States.
Terrorism--United States--Prevention.
Terrorists--United States.
War on Terrorism, 2001-2009.