1. D. McLean, “Grain Boundaries in Metals” (Clarendon Press, Oxford, 1957).
2. R. C. Gifkins, in “Fracture”, edited by B. C. Averbach, D. K. Felbeck, G. T. Hahn and D. A. Thomas (Wiley Interscience, New York, 1959) p. 579.
3. H. Conrad, in “Mechanical Behavior of Materials at Elevated Temperatures”, edited by J. E. Dorn (McGraw-Hill, New York, 1961) p. 218.
4. A. H. Cottrell, Intercrystalline Creep Fractures, in “Structural Processes in Creep” (Iron and Steel Institute, London, 1961) p. 1.
5. F. Garofalo, “Fundamentals of Creep and Creep-Rupture in Metals” (Macmillan Company, New York, 1965).