1. Aldrich Mark (1970) History of workplace safety in the United States1880–1970. See http://eh.net/encyclopedia/history-of-workplace-safety-in-the-united-states-1880-1970/
2. Aldrich M (1997) Safety first: technology, labor and business in the building of work safety, 1870–1939. Johns Hopkins University Press, Baltimore
3. Aldrich M (1999) The peril of the broken rail: the carriers, the steel companies, and rail technology, 1900–1945. Technol Cult 40(2):263–291
4. Annual report (1870) Massachusetts Bureau of Statistics of Labor. 197
5. Annual report (1972) Massachusetts Bureau of Statistics of Labor. pp 421–25