Wage rates and working time in the bituminous coal industry, 1912-1922 : with a summary of rates for separate occupations in each coal district in the United States
著者
書誌事項
Wage rates and working time in the bituminous coal industry, 1912-1922 : with a summary of rates for separate occupations in each coal district in the United States
（Research studies / Industrial Research Department, Wharton School of Finance and Commerce, University of Pennsylvania, 21）
University of Pennsylvania Press, 1932