1. DIRECT EXPERIMENTAL EVIDENCE OF DISLOCATIONS
2. See H.J. Gough, Proc. ASTM 33: 3. 1933; the ASTM index to technical papers and reports (1898-1950); the ASTM collections of references on fatigue, published annually since 1950; and the ASTM symposia published as special technical reports. A recent book is Fatigue of Metals, by P.G. Forrest, Pergamon (Addison-Wesley International), 1962.