1994GB/T 223.20-1994 Methods for chemical analysis of iron steel and alloy.The Potentiometric titration method for the determination of cobalt content
1982GB 223.20-1982 Chemical analysis of iron,steel and alloy--The determination of cobalt by the potentiometric titration method
GB 223.20-1982 Chemical analysis of iron,steel and alloy--The determination of cobalt by the potentiometric titration method was changed to GB/T 223.20-1994 Methods for chemical analysis of iron steel and alloy.The Potentiometric titration method for the determination of cobalt content.