1. 1) HOWER and ANTHES: Iron and Steel Engineer, (1956) Feb., p.60
2. 3) CHARLES: Min. Eng., 9 (1957) p.80
3. 4) TAGGART: Handbook of Mineral Dressing.(1945)
4. 5) DEVANEY: U.S. Pat. 2, 960, 396 (Nov. 15, 1960)
5. 8) LINDER: J. Iron & Steel Inst.(U. K.), 189 (1958), p.233