American Engineering Standards Committee , American Drop Forging Institute and National Safety Council. Safety Code for Forging and Hot Metal Stamping : Tentative American Standard, Approved April 8, 1927, American Engineering Standards Committee : Bulletin of the United States Bureau of Labor Statistics, No. 451 , Washington, D.C: G.P.O., August 1927, https://fraser.stlouisfed.org/title/4045, accessed on December 20, 2024.