United States. Bureau of Labor Statistics. "National Compensation Survey: Occupational Wages in the East North Central Census Division, 1999 : Bulletin of the United States Bureau of Labor Statistics, No. 2544-3," National Compensation Survey: Occupational Wages in the United States (July 2001). https://fraser.stlouisfed.org/title/6084/item/584705, accessed on January 16, 2025.