1. 1) J. R. E. Arthur : New techniques to measure new parameters, Proc. of Eoscoe Material Symp. on Stress-Strain Behavior of soils, Cambridge, (1971), pp.340-346.
2. 2) F. Verhelst, A. Vervoort, PH. de Bosscher and G. Marchal : X-ray computerized tomography, Determination of heterogeneities in rock sample, Proc. of 8th ISRM Cong. Tokyo, 1(1995), 105-108.
3. 3) T. Nakano, K. Nakamura, T. Someya and H. Otsuka : Observation of 3-dimnsional internal structure of rock using X-ray CT, (1) Density calibration of CT value, Geoinfomatics, 8(1997), 239-255.
4. Crack Opening Analysis by means of the X-Rays CT.
5. 5) V. Cromwell, D. J. Kortum and D. J. Bradley : The use of a medical computer tomography (CT) system to observe multi phase flow in porous media, Soc. of Petroleum Eng., 13098, Soc. Petroleum Eng., Richardson, TX, (1984).