Columbia subject headings:
Eavesdropping--United States.
Wiretapping--Germany (West)
Wiretapping--United States.
Harvard subject headings:
Eavesdropping--United States
Wiretapping--Germany (West)
Wiretapping--United States.
Princeton subject headings:
Eavesdropping--United States.
Wiretapping--Germany (West).
Wiretapping--United States.