United States. Bureau of Labor Statistics. "Unemployed Persons by Reason for Unemployment, Sex, Age, and Color," in United States. Bureau of Labor Statistics. "April 1971," The Employment Situation (May 7, 1971) : 9-9. https://fraser.stlouisfed.org/title/144/item/496971/toc/513090 , accessed on May 2, 2024.