"Falls of roof in mines operating in the Pittsburgh coal bed, West Virginia. "; "Paul, James Washington.", "Geyer, John Nicholas, 1896-"; "Coal mine accidents.", "Coal mines and mining--West Virginia."; "Geyer, John Nicholas, 1896-", "Paul, James Washington."; "1933"; "Government document. Issued as: United States. Department of Commerce. Bureau of Mines. Technical paper, 547. "; ""; "P3216"; "pec"; "Coal mine accidents.", "Coal mines and mining--West Virginia."; "14256"; .