01263oam 2200361 450 991070454680332120170517130156.0(CKB)5470000002442237(OCoLC)987379266(EXLCZ)99547000000244223720170517d2012 ua 0engurbn|||||||||txtrdacontentcrdamediacrrdacarrierPillar recovery design, technologies, and procedures in roof control plan reviewsArlington, Virginia :U.S. Department of Labor, Mine Safety and Health Administration,2012.1 online resource (5 pages)Procedure instruction letter ;no. I12-V-02"Effective date: 02/16/2012; expiration date: 03/21/2014."Mine safetyUnited StatesBarrier pillarsSafety measuresMine safetyBarrier pillarsSafety measures.United States.Mine Safety and Health Administration,GPOGPOGPOBOOK9910704546803321Pillar recovery design, technologies, and procedures in roof control plan reviews3343490UNINA