01181nam 2200325Ka 450 991069672840332120080716083314.0(CKB)5470000002381590(OCoLC)234072517(EXLCZ)99547000000238159020080716d1983 ua 0engtxtrdacontentcrdamediacrrdacarrierVertical magnetic noise in the voice frequency band within and above coal mines[electronic resource] /by John Durkin[Washington, D.C.] :U.S. Dept. of the Interior, Bureau of Mines,[1983]27 pages digital, PDF fileReport of investigations ;8828Title from title screen (viewed on July 14, 2008).Coal mines and miningCommunication systemsCoal mines and miningCommunication systems.Durkin John1391019United States.Bureau of Mines.GPOGPOBOOK9910696728403321Vertical magnetic noise in the voice frequency band within and above coal mines3543855UNINA