United States. Bureau of Labor Statistics. "Area Wage Survey: The Allentown-Bethlehem-Easton, Pennsylvania-New Jersey, Metropolitan Area, May 1969 : Bulletin of the United States Bureau of Labor Statistics, No. 1625-86," Area Wage Survey (1969). https://fraser.stlouisfed.org/title/4655/item/498531, accessed on January 16, 2025.