1. 1) Y. Obara, T. Shin, T. Yoshinaga: Journal of MMIJ, 127 (2011) , 20-25.
2. 2) Y. Obara, T. Shin, T. Yoshinaga, K. Sugawara, S.S. Kang: Proc. of Int. Symp. on In-situ Rock Stress, Beijing, (2010) , pp. 129-134.
3. 3) Y. Obara, Y. Fukushima, T. Yoshinaga, T. Shin, M. Ujihara, S. Kimura, T. Yokoyama: Proc. of Int. Congr. on ISRM, Beijing, (2011) , to be appeared.
4. 4) T. Kiguchi, Y. Kuwahara, T. Yokoyama: Proc. of MMIJ Fall Meeting Sapporo, (2009) , pp. 309-312.
5. 5) K. Kawabe, F. Sugimoto, T. Imai: Journal of MMIJ, 121 (2005) , 378-386.