1. The Preparation of Maps and Plans in Terms of Engineering Geology,;Q. Jl Engng. Geol.,,1972
2. Barton, N., Lien, R., & Lunde, J. 1974. Engineering Classification of Rock Masses for the Design of Tunnel Support. Norwegian Geotech. Inst. Pub. No. 106.
3. Beniawski, Z. T., 1973. Engineering Classification of Jointed Rock Masses. The Civil Engnr in South Africa, 335–343.
4. Broadbent, C. D. & Rippere, K. H. 1970. Fracture Studies at Kimberley Pit. Planning Open Pit Mines, South Africa Inst. Min. Met., 171–179.
5. Cottiss, G. I., Dowell, R. W. & Franklin, J. A. 1971. A Rock Classification System applied to Civil Engineering. Civil Engng. & Public Works Review, 611–614 & 736–738.