http://pec.lib.wvu.edu/record/P194581947Installation of a model man cage at the Avoca Shaft of the Heidelberg Coal Co., Avoca, Luzerne County, Pa.<p> Serial issue. Issued as: United States. Bureau of Mines. <em>Information circular</em>, 7407 (1947).</p>Mather, Joseph V.McCleary, E. H.Mine safety.Coal mines and mining--Pennsylvania--Safety measures.14256