United States. Bureau of Labor Statistics. Division of Occupational Outlook. "A Guide to Labor-Management Relations in the United States. Supp. 1 : Bulletin of the United States Bureau of Labor Statistics, No. 1225-1," A Guide to Labour-Management Relations in the United States (November 1958). https://fraser.stlouisfed.org/title/4569/item/495746, accessed on March 5, 2025.