United States. Bureau of Labor Statistics. "Fourth Quarter and Annual Averages, 1987," Productivity and Costs (February 4, 1988). https://fraser.stlouisfed.org/title/131/item/55806, accessed on April 23, 2024.
United States. Bureau of Labor Statistics. "Fourth Quarter and Annual Averages, 1987," Productivity and Costs (February 4, 1988). https://fraser.stlouisfed.org/title/131/item/55806, accessed on April 23, 2024.