Columbia subject headings:
Mobile communication systems--United States.
Radio--Law and legislation--United States.
Telecommunication--Law and legislation--United States.
Telephone--Emergency reporting systems--Law and legislation--United States.
Harvard subject headings:
Mobile communication systems--United States.
Radio--Law and legislation--United States
Telecommunication--Law and legislation--United States
Telephone--Emergency reporting systems--Law and legislation--United States.
Princeton subject headings: