Columbia subject headings:
Eyeglasses--Prices--United States.
Optical trade--United States.
Restraint of trade--United States.
Harvard subject headings:
Eyeglasses--Prices--United States.
Optical trade--United States.
Restraint of trade--United States.
Princeton subject headings:
Eyeglasses--Prices--United States.
Optical trade--United States.
Restraint of trade--United States.