The following reference works are cited in this example problem:
Newman, J. C. & Raju, I. S. (1979). Analysis of surface cracks in finite plates under tension or bending loads. NASA Technical Paper 1578. National Aeronautics and Space Administration.
Kamaya, M. (2006). Stress intensity factor of surface crack with undulated front. JSME International Journal. 49.4: 529-535.
Anderson, T.L. (2005). Fracture mechanics - Fundamentals and applications (3rd. ed.) CRC. Boca Raton.
Rhee H. C. & Salama, M. M. (1987). Mixed-mode stress intensity factor solutions of a warped surface flaw by three-dimensional finite element analysis. Engineering Fracture Mechanics 28.2: 203-209.