Byer, Herman B. , United States. Bureau of Labor Statistics and United States. Works Progress Administration. "East North Central Cities, Volume III" in Salaries and Hours of Labor in Municipal Fire Departments, July 1, 1938 : Bulletin of the United States Bureau of Labor Statistics, No. 684 (1941). https://fraser.stlouisfed.org/scribd/?item_id=494398&filepath=/files/docs/publications/bls/bls_0684-v3_1941.pdf&start_page=1, accessed on August 21, 2017.