Hopkins, W. S. (1948). Labor in the American economy. McGraw-Hill Book Co.
Lua i Stíl Chicago (17ú heag.)Hopkins, William Stephen. Labor in the American Economy. New York: McGraw-Hill Book Co, 1948.
Lua MLA (9ú heag.)Hopkins, William Stephen. Labor in the American Economy. McGraw-Hill Book Co, 1948.
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