Columbia subject headings:
American Telephone and Telegraph Company--History.
Electronics--United States--History.
Telecommunication--United States--History.
Telephone--United States--History.
Harvard subject headings:
American Telephone and Telegraph Company--History.
Electronics--United States--History.
Telecommunication--United States--History.
Telephone companies--United States--History.
Princeton subject headings:
American Telephone and Telegraph Company--History.
Electronics--United States--History.
Telecommunication--United States--History.
Telephone--United States--History.