Harrington, D. & Fene, W. J. Coal-Mine Explosions and Coal- and Metal-Mine Fires in the United States During the Fiscal Year Ended June 30, 1943, report, February 1944; (https://digital.library.unt.edu/ark:/67531/metadc67030/m1/1/: accessed April 26, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .