http://pec.lib.wvu.edu/record/P165621965The Course of pneumoconiosis in coal miners : should a miner with the condition continue to work in dust?Journal article reprint from: <em>Archives of Environmental Health</em>, v.10 (1965:May). Lieben, Jan.Pendergrass, Eugene Percival, 1895-Brieger, Heinrich.Coal miners--Diseases.Pneumoconiosis.Lungs--Dust diseases.14256