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2. Fritz Wiist, Stahl u. Eisen, 48 (1928), 16
3. William Lenning, The Iron Age, Jan. (1929), 10
4. G.E. Rose, Blast Furnace and Steel Plant, Feb. (1931)
5. Dinkler, Fou. Trad. Jou., May 3 (1934), 290.