1. The concept of specific energy in rock drilling;Teale;Int. J. Rock. Mech. Min. Sci.,1965
2. A critical appraisal of the Protodyakonov index;Paithankar;Int. J. Rock. Mech. Min. Sci. & Geomech. Abstr.,1976
3. Normalization of specific energy (Technical Note);Mellor;Int. J. Rock Mech. Min. Sci.,1972
4. The use of irregular specimens for rock strength tests;Brook;Int. J. Rock Mech. Min. Sci. & Geomech. Abstr.,1977
5. Drillability studies—laboratory percussive drilling;Paone,1969