United States. Bureau of Labor Statistics. "Employed and Unemployed Persons by Occupation, Not Seasonally Adjusted," in United States. Bureau of Labor Statistics. "July 2008," The Employment Situation (August 1, 2008) : 17-17. https://fraser.stlouisfed.org/title/144/item/494816/toc/508052 , accessed on April 18, 2024.