United States. Bureau of Labor Statistics. "National Compensation Survey: Philadelphia-Wilmington-Atlantic City, PA-NJ-DE-MD, February 1999 : Bulletin of the United States Bureau of Labor Statistics, No. 3095-58," National Compensation Survey (Wages and Salaries) (September 1999). https://fraser.stlouisfed.org/title/6009/item/582348, accessed on January 8, 2025.