Columbia subject headings:
Hospitals--Employees--Labor unions--Rocky Mountains Region--History.
Miners--Health and hygiene--Rocky Mountains Region--History.
Harvard subject headings:
Hospitals--Employees--Labor unions--Rocky Mountains Region--History.
Miners--Health and hygiene--Rocky Mountains Region--History.
Princeton subject headings:
Hospitals--Employees--Labor unions--Rocky Mountain Region--History.
Miners--Health and hygiene--Rocky Mountain Region--History.