US Department of Labor. Important events in American labor history, 1778, 1968. US Dept. of Labor.
Cita Chicago (17th ed.)US Department of Labor. Important Events in American Labor History, 1778, 1968. Washington D.C: US Dept. of Labor.
Cita MLA (9th ed.)US Department of Labor. Important Events in American Labor History, 1778, 1968. US Dept. of Labor.
Atenció: Aquestes cites poden no estar 100% correctes.