United States. Bureau of Labor Statistics , Nelson, Richard Rex , Breneman, Donald L. and Doster, James L. Collective Bargaining Agreements in the Federal Service, Late 1971 : Bulletin of the United States Bureau of Labor Statistics, No. 1789 , Washington, D.C: U.S. Dept. of Labor, Bureau of Labor Statistics, 1973, https://fraser.stlouisfed.org/title/4673, accessed on September 10, 2024.