United States. Bureau of Labor Statistics. "National Compensation Survey: Chicago-Gary-Kenosha, IL-IN-WI, July 1997 : Bulletin of the United States Bureau of Labor Statistics, No. 3090-28,"
National Compensation Survey (Wages and Salaries)
(Revised March 1999).
https://fraser.stlouisfed.org/title/6009/item/582268, accessed on February 9, 2026.