1. www.Ime.co.uk/nickel_industryusage.asp and The London Metal Exchange Limited, corporate brochure 2003–March 2006.
2. www.inco.com/investorinfo/presentations/pdf/ BMONesbittFebruary2706slides.pdf – March 2006
3. ASTM B 604-91 (2003)e1 App. X1.
4. “Chromic acid” COMAH Rev 2_1,2005