United States. Bureau of Labor Statistics. "Employed and Unemployed Persons by Occupation, Not Seasonally Adjusted," in United States. Bureau of Labor Statistics. "May 2006," The Employment Situation (June 2, 2006) : 15-15. https://fraser.stlouisfed.org/title/144/item/494790/toc/508640 , accessed on April 18, 2024.