1. Gerlach, Ann. Phys., 25, 209 (1936).
2. Löwe, Ann. Phys., 25, 212 (1936).
3. Reid, Phys. Rev., 60, 161 (1941).
4. Price, J. Iron and Steel Inst., Paper No. 7 (1943). Nature, 157, 765 (1946).
5. Mott and Jones "Properties of Metals and Alloys", Chap. 3, p. 120.