1. S. Bergh, “Oxygen Content and Oxides in a Silicon Killed Steel,” Jern. Ann., V. 146, 1962, p. 748–762 (BISI No. 3140).
2. G.W. Walker, “Rating of Inclusions (“Dirt Chart”),” Metal Progress, V. 35, (Feb. 1939), p. 169, 170, 167.
3. H. Diergarten, “Slag Inclusions in Steel. Standards for Size and Frequency,” Metal Progress, V. 32, Sept. 1937, p. 269–271.
4. H. Qiergarten, “Classification of Roller Bearing Steels According to Inclusion Content,” Arch. Eisenhutten., V. 10, 1936, p. 197–210 (HB No. 556).
5. ASTM A317, “Standard Method of Macroetch Testing and Inspection of Steel Forgings”