Rice, George S.; Paul, J. W. & Greenwald, H. P. Coal-Dust Explosion Tests in the Experimental Mine, 1919 to 1924, Inclusive, report, 1927; (https://digital.library.unt.edu/ark:/67531/metadc12447/m1/1/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .