Thank you everyone! I need several papers ,Is there anyone who can help me?
1 G.Erdi "Instrumentation Operational Amplifier with low noise ,drift,bias current" in Northeast Res.Eng.Meeting Rec.Tech paper,Oct.1972.
2 "A low drift,low noise monolithic operational amplifier for low level signal processing" Fairchild Semiconductor,Application Brief 136,July 1969.