1. Which side are you on? The Harlan County coal miners, 1931–39;Hevener,1978
2. Method of eliminating coal bumps or minimizing their effects;Bryson;AIME Trans,1936
3. USBM IC 6872: Methods of development and pillar extraction mining in the Pittsburgh coalbed in PA, WV, and OH;Paul,1935
4. NIOSH. Research report on coal pillar recovery under deep cover; 2010.
5. Amount and nature of losses in mining bituminous coal in eastern United States;Rice;Annex to the Report of the United States Coal Commission on Waste of Coal in Mining,1923