United States. Bureau of Labor Statistics. "National Survey of Professional, Administrative, Technical, and Clerical Pay, June 1968 : Bulletin of the United States Bureau of Labor Statistics, No. 1617,"
National Survey of Professional, Administrative, Technical, and Clerical Pay
(1969).
https://fraser.stlouisfed.org/title/4570/item/498438, accessed on March 16, 2025.