http://pec.lib.wvu.edu/record/P194711940Methods of sampling and analyzing coal-mine dusts for incombustible content.<p> Serial issue. Issued as: United States. Bureau of Mines. <em>Information circular</em>, 7113 (1940:July).</p>Owings, C. W. (Clarence Watson), 1894-Greenwald, H. P. (Harold Putnam), 1893-Selvig, W. A. (Walter Alfred), 1886-1972.Coal dust--Sampling.Coal dust--Analysis. 14256