United States. Bureau of Labor Statistics. "Employed and Unemployed Persons by Occupation, Not Seasonally Adjusted," in United States. Bureau of Labor Statistics. "August 2007," The Employment Situation (September 7, 2007) : 17-17. https://fraser.stlouisfed.org/title/144/item/494805/toc/508307 , accessed on April 18, 2024.