Columbia subject headings:
Telephone companies--Employees--Labor unions--United States--History.
Telephone operators--United States--History.
Women labor union members--United States--History.
Harvard subject headings:
Telephone companies--Employees--Labor unions--United States--History.
Telephone operators--United States--History.
Women labor union members--United States--History.
Princeton subject headings:
Telephone companies--Employees--Labor unions--United States--History.
Telephone operators--United States--History.
Women labor union members--United States--History.