1. Appleton, W. C. and J. G. Baker. “The Effect of Unionization on Safety in Bituminous Deep Mines.”Journal of Labor Research 5 (Spring 1984): 139–147.
2. Boden, L. “Underground Coal Mine Accidents and Government Enforcement of Safety Regulations.” Ph.D dissertation, MIT, Boston, 1976.
3. Hannah, R. L. “A Case Study of Underground Coal Mining Productivity in Utah.” Ph.D. dissertation, University of Utah, Salt Lake City, 1981.
4. Hollis, R. G. “Managers Attitudes: Union vs. Non-Union.”Coal Mining and Processing (May 1979), pp. 62–66.
5. National Research Council.Towards Safer Underground Coal Mines. Washington, D.C.: National Academy Press, 1982.