1. A Study of Energy Transfer to Rock and Prediction of Drilling Rates in Percussive Drilling;Hustrulid,1965
2. Hustrulid W. A. Unpublished Research, Atlas Copco AB, Stockholm, Sweden (1965–1966).
3. A Theoretical and Experimental Study of Percussive Drilling of Rock;Hustrulid,1968
4. Rock Drillability for Military Applications;Paone,1968
5. Madsen R. Personal communication, Twin Cities Mining Research Center, United States Bureau of Mines, April (1968).