1. Development of an experimental ripping machine;Peake;Trans, Inst. Min. Eng.,1960
2. Further experiments with the Peake ripping machine;Parkes;Min. Eng.,1962
3. Demonstration of continuous ripper;Anon;Colliery Engng.,1963
4. A simple method for assessing the uniaxial compressive strength of rock;Hobbs;Int. J. Rock Mech. Mining Sci.,1964