United States. Bureau of Labor Statistics. "National Compensation Survey: Grand Rapids-Muskegon-Holland, MI, April 2006 : Bulletin of the United States Bureau of Labor Statistics, No. 3135-27," National Compensation Survey (Wages and Salaries) (December 2006). https://fraser.stlouisfed.org/title/6009/item/582939, accessed on January 24, 2025.