1. NASIATKA, T. M., Tunnelling Technology—Its Past and Present, US Bur. Min., Inf. Circ. No. 8365, 1968.
2. Hard rock tunnelling machines;MUIRHEAD;Bull. Instn Min. Metall.,1969
3. BRUCE, W. E., and MORRELL, R. J., Principles of rock cutting applied to mechanical boring machines, Proc. 2nd Symp. on Rapid Excavation, Sacramento State College, October 1969, paper 3, pp. 1–43.
4. The mechanical excavation of rock—experiments with roller cutters;TEALE;Int. J. Rock Mech. Min. Sci.,1964
5. ROBBINS, R. J., Economic factors in tunnel boring, Proc. S. African Inst. Tunnelling Conf., Johannesburg, 1970.