1. A. P. Bobryakov, “Determination of the energy expenditure under impact cleavage of solids,” Questions of the Fracture Mechanism of Mountain Rock [in Russian], Mining Inst. Sib. Branch, Academy of Sciences of the USSR (1976).
2. V. P. Efimov and E. N. Sher, “Analysis of parameters for insertion of a stiff wedge in a specimen with a slit,” Fiz.-Tekh. Probl. Razrab. Polezn. Iskop., No. 1 (1989).
3. P. S. Theocaris, “Local flow near the crack apex in plexiglass,” Prikl. Mekh., No. 2 (1970).
4. P. S. Theocaris, “Complex stress intensity factor at bifurcated cracks,” J. Mech. Phys. Solids,20 (1972).
5. P. Manogg, Ph.D. Thesis, Univ. Freiburg [in German] (1964).