United States. Bureau of Labor Statistics. Division of Occupational Outlook. Analysis of Health and Insurance Plans Under Collective Bargaining, Late 1955: Life Insurance, Accidental Death and Dismemberment, Accident and Sickness, Hospitalization, Surgical, Medical, Maternity : Bulletin of the United States Bureau of Labor Statistics, No. 1221 , November 1957, https://fraser.stlouisfed.org/title/4501, accessed on September 25, 2024.