1. J. I. Bluhm, The Effect of Nonlinear Hertzian Deformations and Gage Length on the Measurement of Elastic Energy Release Rate, J. of Materials, 2, 1 (1967) 227–236.
2. J. E. Srawley, M. H. Jones and B. Gross, Experimental Determination of the Dependence of Crack Extension Force on Crack Length for a Single-Edge-Notch Tension Specimen, NASA TN D-2396, August 1964.
3. W. T. Koiter, On the Flexural Rigidity of a Beam Weakened by Transverse Saw Cuts, Proc. Kom. Ned. Ak. Wet. Amsterdam, B, 59 (1956)
4. also, J. of Applied Mechanics (1965).
5. O. L. Bowie and D. M. Neal, The Effective Crack Length of an Edge Slot in a Semi-Infinite Sheet Under Tension, International J. of Fracture Mechanics, 3, 2 (1967) 111–119.