1. Aki K. and Richards P. G. (1980). Quantitative seismology theory and methods . Vol. 1 W. H. Freeman and Company New York N.Y.
2. Broek D. (1987). Elementary engineering fracture mechanics . 4th Ed. Martius Nijhoff Hingham Mass.
3. Strain Field Measurement in Fracture Process Zone
4. Courtney T. H. (1989). Mechanical behavior of materials . McGraw‐Hill Publishing Co. New York N.Y. 84–93.