1. Bieniawski, Z.T. and Van Heeden, W.L. (1975) The significance of in situ tests on large rock specimens. International Journal of Rock Mechanics and Mining Sciences, 12, 101?13.
2. Brown, E.T. (ed.) (1981) Rock Characterisation, Testing and Monitoring: ISRM Suggested Methods, International Society for Rock Mechanics, Pergamon, Oxford, for the Commission of Testing Methods, pp 211.
3. CMRS (1992) Workability indices of coal seams. Unpublished Report of an S and T Project, Coal Mining Research Station, Dhanbad, India, pp 64.
4. Evans, I. and Pomeroy, C.D. (1966) The Strength, Fracture and Workability of Coal, Pergamon, Oxford, pp 277.
5. Nishimatsu, Y. (1972) The mechanics of rock cutting. International Journal of Rock Mechanics, Mining Sciences and Geomechanics Abstracts, 25, 71?96.