Columbia subject headings:
Agricultural laborers--Health and hygiene--Congresses.
Agricultural laborers--Health and hygiene--Law and legislation--Congresses.
Agriculture--Safety measures--Congresses.
Harvard subject headings:
Agricultural laborers--Health and hygiene--Congresses.
Agricultural laborers--Health and hygiene--Law and legislation--Congresses.
Agriculture--Safety measures--Congresses.
Princeton subject headings:
Agricultural laborers--Health and hygiene--Congressess.
Agricultural laborers--Health and hygiene--Law and legislation--Congressess.
Agriculture--Safety measures--Congressess.