In general, pig iron and iron and steel scrap form the base of steel. (Mary Katharine Hickey. "History and development of stainless steel and stainless iron")〔1934年〕[1]
↑ Mary Katharine Hickey (1934). History and development of stainless steel and stainless iron (M.B.A. thesis). Boston University. p. 30. https://hdl.handle.net/2144/21460