Third industrial directory of Pennsylvania, 1919 Pennsylvania. Dept. of labor and industry Published: 1920 Total Pages: 1222 Get eBook
Monthly List of State Publications Library of Congress. Division of Documents Published: 1921 Total Pages: 626 Get eBook
Labor and Industry Pennsylvania. Dept. of Labor and Industry Published: 1921 Total Pages: 1026 Get eBook
Library Bulletin Pittsburgh Experiment Station (United States. Bureau of Mines) Published: 1921 Total Pages: 448 Get eBook
