United States. Bureau of Labor Statistics and Wood, Helen. "Employment Opportunities in Aviation Occupations, Duties, Qualifications, Earnings, and Working Conditions : Bulletin of the United States Bureau of Labor Statistics, No. 837-2" in Employment Opportunities in Aviation Occupations : Bulletin of the United States Bureau of Labor Statistics, No. 837 (1947). https://fraser.stlouisfed.org/title/4307/item/495024, accessed on September 18, 2024.