United States. Bureau of Labor Statistics. "Digest of 100 Selected Pension Plans under Collective Bargaining, Spring 1968 : Bulletin of the United States Bureau of Labor Statistics, No. 1597," Digest of 50 Selected Pension Plans for Salaried Employees (1969). https://fraser.stlouisfed.org/title/4696/item/498422, accessed on October 13, 2024.