http://pec.lib.wvu.edu/record/P194661936Some suggestions on the safe handling of electric shovel trailing cables in open-pit mines.<p> Serial issue. Issued as: United States. Bureau of Mines. <em>Information circular</em>, 6922 (1936:Nov.).</p>Crawford, F. S.Mining machinery--Electric equipment.Mine safety.Electric cables.Coal mines and mining--Electric equipment.14256