Columbia subject headings:
Employee rights--United States.
Packing-house workers--United States.
Slaughtering and slaughter-houses--United States.
Harvard subject headings:
Employee rights--United States
Packing-house workers--United States.
Slaughtering and slaughter-houses--United States
Princeton subject headings:
Employee rights--United States.
Packing-house workers--United States.
Slaughtering and slaughter-houses--United States.