1. 3) Rosenhain and Archbutt: Trans, Royal Soc., 212 (1912), 315.
2. 4) Hanson and Gaylor: Inst. Metal, 27 (1922) 267.
3. 5) Hanson, Gaylor: Inst. Metal, 27 (1922) 267.
4. 1) Fraenkel u. Goez: Zeits Metallk., 17 (1925), 12
5. Fraenkel u. Wachsmuth: Zeits Metallk., 22 (1930), 163.