Coal-Mine Ventilation Factors, report, 1929; (https://digital.library.unt.edu/ark:/67531/metadc12463/m1/4/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .
Coal-Mine Ventilation Factors, report, 1929; (https://digital.library.unt.edu/ark:/67531/metadc12463/m1/4/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .