United States. Bureau of Labor Statistics. "Tomorrow's Manpower Needs: Volume IV" in Tomorrow's Manpower Needs: National Manpower Projections and a Guide to Their Use as a Tool in Developing State and Area Manpower Projections : Bulletin of the United States Bureau of Labor Statistics, No. 1606 (1969). https://fraser.stlouisfed.org/title/4863/item/498430, accessed on September 29, 2022.