United States. Bureau of Labor Statistics. "Employed and Unemployed Persons by Occupation, Not Seasonally Adjusted," in United States. Bureau of Labor Statistics. "September 2012," The Employment Situation (October 5, 2012) : 24-24. https://fraser.stlouisfed.org/title/144/item/494866/toc/506677 , accessed on April 23, 2024.