Permissible Methane Detectors, report, 1930; (https://digital.library.unt.edu/ark:/67531/metadc12501/m1/1/: accessed May 1, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .
Permissible Methane Detectors, report, 1930; (https://digital.library.unt.edu/ark:/67531/metadc12501/m1/1/: accessed May 1, 2024), University of North Texas Libraries, UNT Digital Library, digital.library.unt.edu; .