^ 1.01.1Jessica Elzea Kogel; Nikhil C. Trivedi; James M. Barker; Stanley T. Krukowski. Industrial Minerals & Rocks 7th. SME. 2006: 156 [2009-07-21]. ISBN 9780873352338. (原始内容存档于2021-07-05).引用错误:带有name属性“Kogel2006”的<ref>标签用不同内容定义了多次
^Iron Age, Vol. LVII, p.871, cited by Journal of the Iron and Steel Institute, Volume 50, Issue 2, p.482