1. T. Yokobori and M. Yoshida,Rep. Res. Inst. Strength and Fracture of Materials, Tohoku Univ. Sendai, Japan 4 (1968) 11;Int. J. Fract. Mech., 4, 2 (1968) 179.
2. T. Yokobori and A. Kamei, Presented at the Symposium on Fracture and Fatigue, George Washington Univ., May, 1972,Engng. Fracture Mech., (in Press).
3. J. Rice,Fracture, H. Liebowitzed. Academic Press, New York, 2 (1968).
4. M. Ogasawara, M. Iino and H. Mimura,Trans. Japan Inst. Metals, 13 (1972) 6.
5. A. Otsuka and K. Mori,Proc. of the 17th Japan National Symposium on Strength, Fracture and Fatigue, Japan Soc. Metals, (1972) 43.