http://pec.lib.wvu.edu/record/P165631964Comparison of dust exposures in Pennsylvania anthracite and bituminous coal mines. Journal article reprint from: <em>American Industrial Hygiene Association Journal,</em> v.25 (1964:Sept./Oct). Baier, Edward J.Diakun, R.Coal miners--Diseases--Pennsylvania.Coal mines and mining--Pennsylvania.Coal dust--Measurement--Pennsylvania.Pneumoconiosis.14256