1. Suggested methods for the quantitative description of discontinuities in rock masses;International Society for Rock Mechanics, Commission on Standardization of Laboratory and Field Tests;Int. J. Rock Mech. Min. Sci. & Geomech. Abstr.,1978
2. Discontinuity frequency in soils and rocks;Hudson,1981
3. Characteristing rock mass jointing patterns;La Pointe,1981
4. Describing the size of discontinuities;Cruden;Int. J. Rock Mech. Min. Sci. & Geomech. Abstr.,1977
5. Statistics;Harper,1971