http://pec.lib.wvu.edu/record/P194761945Testing safety catches on mine cages, Lake Superior district.<p> Serial issue. Issued as: United States. Bureau of Mines. <em>Information circular,</em> 7325 (1945:June).</p>Pearce, Clyde M.Cash, Frank E. (Frank Errette)Iron mines and mining--Safety appliances--Lake States--Equipment and supplies.14256