1. NATURE, 138, 331 (August 22, 1936).
2. J. Iron and Steel Inst., 110, 317 (1924).
3. J. Iron and Steel Inst., 112, 98, Fig. 9 (1925).
4. E. W. Fell, ” The Piobert Effect in Iron and Soft Steel”, J. Iron and Steel Inst., 132, 75 (1935).
5. J. Iron and Steel Inst., 133, 389P (1936)